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1 


MONOGRAPHY 


OF  THE 


FAMILY    UNIONIDiE, 


OR  NAIADES  OF  LAMARCK, 


(FRESH  WATER  BIVALVE   SHELLS,) 


OF 


NORTH   AMERICA, 


ILLUSTRATED  BY  FIGURES  DRAWN  ON  STONE  FROM  NATURE. 


BY  T.  A.  CONRAD, 


CURATOR  OF  THE  ACADEMY  OP  NATURAL  SCIENCES  OP  PHILADELPHIA,  HONORARY  MEMBER  OF 
THE  GEOLOGICAL  SOCIETY  OF  PENNSYLVANIA. 


PHILADELPHIA: 

J.  DOBSON,  108  CHESNUT  STREET. 

1836. 


J5  @  CS= — =3= 

LI 


IBRARY    OF 
Illinois  State 

Laboratory  of  Natural  History 

NORMAL,  ILLINOIS 


PanUgranh,  Bloomington.  III. 


E.   G.    DORSEY,   PlUNTER, 

12  Library  Street. 


TO 

CHARLES    A.    POULSON,    Esq. 

Member  of  the  Academy  of  Natural  Sciences  of  Philadelphia,  tyc. 

THIS  BOOK  IS  DEDICATED, 

AS  A  SLIGHT  TRIBUTE  OF  ESTEEM, 

BY  HIS  OBLIGED  FRIEND, 

THE  A  UTHOR. 


MONOGRAPH  Y 


OF  THE 


FAMILY    UNIONIDiE 


UNIO. 

GENERIC  CHARACTER. 

Shell  equivalved,  inequilateral:  cardinal  teeth  two 
in  each  valve,  irregular,  generally  striated,  simple  or 
biparted;  an  elongated  lamelliform  tooth  on  the  pos- 
terior hinge  margin  of  the  right  valve,  and  two 
similar  teeth  on  the  corresponding  margin  of  the  left 
valve:  muscular  impressions  two  principal  ones  in 
each  valve. 

OBSERVATIONS. 

Mr.  Say  justly  remarks,  that,  "in  North  America, 
the  shells  of  this  genus  excel  those  of  any  other 
country  in  magnitude,  beauty,  and  diversity  of  spe- 
cies." The  rivers  of  Tennessee  have  furnished  the 
most  beautiful  specimens  of  many  species  common  to 
the  western  waters.     The  Ohio  or  Mississippi  has 


not  hitherto  furnished  a  single  species  existing  in 
tide  waters  which  flow  into  the  Atlantic;  and  the 
only  shell  of  this  character  is  the  Alasmodonta  mar- 
ginata,  Say. 

The  shells  of  this  genus  may  be  divided  into  two 
groups,  the  "winged"  and  "not  winged,"  as  Mr.  Sow- 
erby  has  proposed  for  the  whole  family  of  Unionid^e. 
The  former  are  included  in  the  genus  Symphy?iota,  of 
Mr.  Lea,  which  we  cannot  adopt,  because,  as  Fe- 
russac  justly  remarks,  "in  the  same  family  generic 
characters  should  be  taken  from  the  same  parts;" 
thus  the  other  genera  are  formed  from  the  absence 
or  arrangement  of  the  hinge  teeth,  whilst  Symphy?wta, 
without  any  regard  to  the  hinge,  is  constructed  from 
a  testaceous  connexion  of  the  valves,  which  Ferussac 
observes  is  "almost  an  organic  character  among  the 
Acephala  which  have  the  mantle  completely  closed 
near  the  hinge  margin,  at  least  in  young  shells." 

Dr.  Kirtland  has  made  some  interesting  remarks 
on  the  sexes  of  this  family,  in  which  he  has  proved 
them  to  be  distinct,  in  the  opinion  of  many  concho- 
logists;  and  the  sex  can  be  ascertained  by  the  form 
of  the  shell.  Almost  every  species  has  two  promi- 
nent varieties  of  form,  one  of  which  is  shorter  and 
more  ventricose  than  the  other,  which  is  happily  ex- 
plained by  the  observations  of  the  intelligent  author 
of  the  essay  referred  to.* 

♦Vide  Silliman's  Journ.  vol.  xxvi.  p.  117. 


UNIO  FASCIATUS. 

Plate  I. 

DESCRIPTION. 

Shell  elliptical,  compressed,  yellowish  olive,  with 
broad  dark  green  rays,  and  a  few  intermediate  nar- 
row rays;  umbo  slightly  compressed,  little  promi- 
nent; anterior  side  short;  ligament  margin  scarcely 
curved,  slightly  declining;  posterior  margin  obliquely 
truncated;  umbonial  slope  abruptly  rounded;  submar- 
gin  slightly  furrowed;  basal  margin  protruding  a 
little  near  and  behind  the  middle;  within  white; 
cardinal  teeth  thick,  direct;  margin  thin,  showing  the 
exterior  rays. 

SYNONYMES. 

U.   fasciatus,  Raf.     Ann.  gen.  des   Sc.  Phys.  vol.  v.  p.  28. 

Poulson's   translation,   p.   20.      Say,  Amer.   Conch.   No.  6. 

Ferussac,  Mag.  de  Zool. 
U.  carinatus,  Barnes.     Silliman's  Journal,  vol.  vi.  p.  126. 
Cab.  Jl.  N.  S.  No.  1020. 

OBSERVATIONS. 

This  shell  has  been  considered  a  variety  of  cario- 
sus  by  some  conchologists,  but  it  is  invariably  more 
ponderous  and  compressed,  with  very  different  mark- 
ings and  cardinal  teeth.  It  is  most  nearly  related  to 
the  crassus,  Say,  but  can  be  distinguished  by  its 
more  elliptical  outline,  much  broader  and  darker  rays, 
and  by  the  beaks  being  less  nearly  terminal.  Fe- 
russac gives  carinatus,  Barnes,  as  a  synonyme  to 
crassus,  Say.     Common  in  the  western  waters.     The 


figure  is  from  a  specimen  from  the  Scioto,  given  me 
by  my  friend,  Dr.  William  Blanding. 


UNIO  OVATUS. 

Plate  II. 
DESCRIPTION. 

Shell  subtriangular,  rather  thin,  compressed  ante- 
riorly, inflated  over  the  mnbonial  slope,  which  is  pro- 
foundly angulated  and  subrectilinear;  posterior  slope 
flattened  or  slightly  concave,  much  wrinkled;  umbo 
inflated,  prominent,  sloping  anteriorly,  distant  from 
the  anterior  margin;  surface  glabrous,  olive-yellow; 
within  bluish;  cardinal  teeth  double  in  each  valve, 
very  oblique,  compressed,  elevated. 

SYNONYMES. 

U.  ovatus,  Say.     Nicholson's  Ency.  (3d  Amer.  ed.)  art-  Conch. 

pi.  ii.  fig.  7.     Lam.  An.  sans  vert.  vol.  vi.  p.  75. 
Cab.  J.  N.  S.  No.  1225. 

OBSERVATIONS. 

The  great  depression  of  the  posterior  slope  distin- 
guishes this  species  from  the  cardium,  Raf.  Old 
shells  are  produced  posteriorly.  It  varies  consider- 
ably in  form;  some  specimens  are  compressed,  others 
very  ventricose,  with  rather  broad  radii  over  the 
whole  disk.  This  variety  is  so  dissimilar  to  the 
specimen  figured,  that  I  propose  to  designate  it  by 
a  distinct  name,  terming  it  variety  ornatus;  it  is  com- 
mon in  the  rivers  of  South  Alabama.  The  species  is 
common  in  the  western  waters. 


5 


UNIO  CLAVA. 

Plate  III.— Fig.  1, 

DESCRIPTION. 

Shell  cuneiform,  very  oblique;  posterior  side  pro- 
duced, compressed,  with  an  oblique  furrow  rapidly 
widening  from  the  umbo;  ligament  margin  arcuate, 
very  oblique;  umbo  elevated,  narrowed,  inclining  for- 
wards; beaks  curved  to  a  point,  terminal;  epidermis 
wrinkled,  olive-yellow  or  brownish,  with  interrupted 
rays  over  the  umbo,  disappearing  with  age;  within 
white,  very  iridescent  posteriorly;  cardinal  tooth  in 
the  left  valve  nearly  parallel  with  the  ligament  mar- 
gin. 

SYNONYMES. 

U.  clava,  Lam.     An.  sans  vert.  vol.  vi.  p.  74. 

U.  scalenius,  Raf.     Ann.  gen.  des  Sc.  Phys.  vol.  v.  p.  43.  pi. 

Ixxxi.  fig.  24,  25.     Poulson's  trans,  p.  47. 
U.  modioliformis,  Say. 
Cab.  A.  N.  S.  No.  1117. 

OBSERVATIONS. 

A  beautiful  species  when  perfect,  and  common  in 
the  western  rivers.  With  age  the  posterior  side  be- 
comes greatly  produced  and  compressed,  and  gene- 
rally furnished  with  irregular  indentations.  Allied  to 
U.  oviformis,  nob.  and  decisus,  Lea. 

B 


G 


UNIO  DECISUS. 

Plate  III.— Fig.  2. 

DESCRIPTION. 

Shell  cuneiform,  oblique;  anterior  margin  obtusely 
rounded;  posterior  side  produced,  somewhat  com- 
pressed, with  a  very  oblique  indistinct  furrow,  and 
irregular  indentations,  frequently  obsolete;  extremity 
angular;  beaks  nearly  terminal,  eroded;  umbonial 
slope  rectilinear,  subangulated;  epidermis  finely  wrin- 
kled inferiorly,  reddish-brown  with  obsolete  brown 
narrow  rays;  within  white. 

SYNONYMES. 

U.  decisus,  Lea.     Trans.   Amer.  Philos.  Soc.  new  series,  vol. 

iv.  p.  92,  pi.  xii.  fig.  23. 
U.  taitianus,  ib.  vol.  v.  p.  39,  pi.  iv.  fig.  11.  variety. 
Cab.  Ji.  N.  S.  No.  1733. 

OBSERVATIONS. 

This  species  much  resembles  the  preceding,  but 
can  always  be  distinguished  by  its  broader  and  less 
oblique  umbo,  uniform  absence  of  green  rays,  and 
by  its  rectilinear  umbonial  slope,  but  more  especially 
by  the  posterior  extremity,  which  is  never  so  nearly 
on  a  line  with  the  base  as  in  the  former  shell,  which 
with  age  is  greatly  produced  and  compressed,  whilst 
the  present  species,  when  old,  never  becomes  so; 
the  cardinal  teeth,  also,  are  very  different.  Com- 
mon in  the  Alabama  river,  and  has  hitherto  been 
found  only  in  the  state  of  Alabama. 


UNIO  REFLEXUS. 

Plate  IV.— Fig.  1. 

DESCRIPTION. 

Shell  suboval,  thick  anteriorly;  middle  of  the  disks 
with  a  single  row  of  distant  elevated  tubercles,  about 
four  in  number;  umbo  not  very  prominent,  subme- 
dial;  umbonial  slope  subcarinated;  posterior  side 
slightly  furrowed  and  emarginate  at  base;  posterior 
slope  flattened,  with  transverse  undulations;  poste- 
rior extremity  truncated;  within  white;  cardinal  teeth 
large,  direct,  much  sulcated. 

Var.  A.  disks  covered  with  small  tubercles. 

Var.  B.  epidermis  blackish,  nacre  purple. 

SYNONYMES. 

U.  reflexus,  Rqf.     Ann.   gen.   des   Sc.  Phys.  vol.  v.  p.  40. 

Poulson's  trans,  p.  40.     Say,  Amer.  Conch.  No.  6.    Ferussac, 

Mag.  de  Zool. 
U.  cornuttjs,  Barnes.     Silliman's  Journ.  vol.  vi.  p.  122. 
Cab.  A.  N.  S.  No.  1750. 

OBSERVATIONS. 

Allied  to  the  U.  flexitosus,  but  approaches  nearest 
to  U.  gibbosus,  Raf.,  yet  may  always  be  distinguish- 
ed from  that  species  by  its  suboval  outline,  and  the 
regularity  and  prominence  of  its  tubercles.  The 
two  varieties  I  found  in  the  Alabama  river.  The 
figure  represents  a  tuberculated  specimen.  The 
species  preserves  its  distinctive  characters  in  very 


8 

remote  localities,  specimens  from  south  Alabama 
perfectly  resembling  others  from  the  waters  of  Indi- 
ana. 


UNIO  FLEXUOSUS. 

Plate  IV.— Fig.  2. 

DESCRIPTION. 

Shell  subtriangular,  bifurcated,  swelling  and  sub- 
nodulous  in  the  middle;  posterior  side  with  a  wide 
oblique  furrow;  umbonial  slope  obtusely  carinated; 
umbo  flattened,  prominent;  epidermis  with  numerous 
slender  rays;  within  white,  cardinal  teeth  direct, 
sulcated;  lateral  teeth  short  and  thick. 

SYNONYMES. 

U.  flexuosus,  Raf.     Ann.  gen.  des  Sc.  Phys.  vol.  v.  p.  40. 
U.  foliatus,  Hildreth.     Silliman's  Journ.  vol.  xiv.  p.  248,  fig. 

16. 
Cab.  A.  N.  S.  No.  1050. 

OBSERVATIONS. 

A  specimen  of  this  shell  in  Mr.  Poul  son's  cabinet 
was  labelled  by  Rafinesque,  whose  description,  un- 
der the  name  we  have  adopted,  entirely  accords  with 
the  species  before  it  has  attained  its  profound  bifur- 
cation. 

This  singular  species,  when  young,  is  smooth,  and 
simply  emarginate  behind  the  middle.  It  approaches 
nearest  to  U.  gibbosus,  Raf.  Not  uncommon  in  the 
western  rivers. 


UNIO  PHILLIPSII. 

Plate  V.— Fig.  1. 

DESCRIPTION. 

Shell  subovate,  with  concentric  furrows;  anterior 
side  smooth;  disk  with  a  single  row  of  irregular 
tubercles  in  the  centre,  some  of  which  are  elongated 
and  grooved;  posterior  side  narrowed,  with  a  wide 
furrow  and  a  few  small  tubercles;  umbonial  slope 
straight,  carinated  and  tuberculated;  posterior  slope 
concave,  indistinctly  tuberculated;  ligament  slope 
rectilinear,  oblique;  extremity  direct,  emarginate; 
basal  margin  swelling  centrally,  emarginate  behind; 
umbo  prominent,  rather  broad,  flattened  at  the  sum- 
mit; beaks  retuse;  epidermis  yellowish-brown,  with 
indistinct  filiform  rays  over  the  umbo;  within  white; 
cardinal  teeth  rather  small,  direct,  double  in  each 
valve. 

OBSERVATIONS. 

This  handsome  species  is  allied  to  U.  quadridas, 
Raf.,  but  is  very  distinct,  the  young  shell  having 
broad  smooth  and  retuse  beaks,  whilst  the  young  of 
the  quadrulus  has  the  beaks  narrowed,  tuberculated, 
pointed  and  curved  forwards.  The  specimen  figured 
is  from  the  Wabash,  and  is  in  the  cabinet  of  Mr. 
John  Phillips,  who  called  my  attention  to  it  as  a 
distinct  species,  and  I  have  dedicated  to  him  a  small 
tribute  of  respect  for  his  talents  and  scientific  zeal. 


10 


UNIO  METANEVRUS. 

Plate  V.— Fig.  2. 
DESCRIPTION. 

Shell  suboval,  thick,  ventricose;  anterior  side  tu- 
berculated,  except  near  the  margin,  which  is  smooth; 
disk  with  an  oblique  furrow;  umbonial  slope  very 
prominent,  broad  and  rounded,  with  numerous  tu- 
bercles, some  of  which  are  very  large;  posterior  slope 
wide,  concave,  or  angular,  with  oblique  slightly  re- 
curved series  of  rib-like  tubercles;  umbo  slightly 
prominent;  beaks  retuse;  ligament  margin  oblique, 
rounded  at  the  extremity;  posterior  margin  emargi- 
nate;  epidermis  yellowish-brown,  with  interrupted 
green  rays;  within  white,  much  thickened  anteriorly. 

SYNONYMES. 

U.  metanevra,  Rctf.     Ann.  gen.  des  Sc  Phys.  vol.  v.  p.  39. 

Ferussac,  Mag.  de  Zool. 
U.  nodosus,  Barnes.     Silliman's  Journal,  vol.  vi.  p.  124,  pi.  vi. 

fig.  7. 
Cab.  Ji.  N.  S.  No.  1754. 

OBSERVATIONS. 

A  common  species  in  the  western  and  southern 
rivers,  easily  recognised,  when  in  perfection,  by  its 
swelling  umbonial  slope:  very  old  specimens  much 
resemble  U.  stapes,  Lea,  but  are  much  larger. 


11 


UNIO  MORTONI. 

Plate  VI.— Fig.  1. 

DESCRIPTION. 

Shell  suborbicular,  not  thick,  ventricose;  disk  flat- 
tened, or  slightly  furrowed  from  beaks  to  base,  co- 
vered with  irregular  tubercles;  anterior  margin  sub- 
truncated;  posterior  margin  straight,  direct;  ligament 
margin  subarcuate,  oblique,  forming  an  angle  with 
the  posterior  margin;  umbo  with  an  oblique  furrow, 
prominent;  beaks  rather  retuse,  decorticated;  umbo- 
nial  slope  angular,  slightly  arcuate;  posterior  slope 
flattened;  epidermis  yellowish  brown,  with  fine  crowd- 
ed wrinkles;  within  white;  anterior  margin  not  thick- 
ened; cardinal  teeth  compressed,  very  prominent, 
oblique. 

Cab.  A.  N.  S.  No.  1874. 

OBSERVATIONS. 

This  pretty  species  is  common  in  Bayou  Teche, 
Louisiana;  but  I  have  seen  it  from  no  other  locality; 
it  approaches  nearest  to  the  quadrulus,  Raf.,  but  dif- 
fers greatly  in  size,  convexity,  and  want  of  a  distinct 
furrow  from  beak  to  base.  It  is  dedicated  to  my 
friend  Dr.  S.  G.  Morton,  whose  exertions  have  fur- 
nished a  splendid  collection  of  American  and  foreign 
fresh  water  shells  to  the  Academy  of  Natural  Sci- 
ences. 


12 


UNIO  FRAGOSUS. 

Plate  VI.— Fig.  2. 
DESCRIPTION. 

Shell  suborbicular,  ventricose,  with  an  indistinct 
narrow  furrow,  and  two  approximate  series  of  very 
prominent  irregular  tubercles,  anterior  ones  largest; 
umbonial  slope  angular;  posterior  slope  slightly  con- 
cave, with  a  few  narrow  rib-like  tubercles,  more  pro- 
minent near  the  margin;  posterior  margin  direct, 
slightly  emarginate;  ligament  slope  straight,  slightly 
oblique;  umbo  narrow,  prominent;  beaks  much  in- 
curved, pointed,  tuberculated;  epidermis  brown,  with 
two  or  three  broad,  widely  interrupted  green  rays. 

OBSERVATIONS. 

This  fine  species  approaches  gaadridus,  Raf.,  but 
is  much  more  ventricose,  has  more  prominent  tuber- 
cles, and  is  very  distinct.  I  am  indebted  to  Dr. 
Blanding  for  the  splendid  specimen  represented  by 
the  figure;  it  is  from  the  Scioto  river,  Ohio. 


17 


UNIO  COSTATUS. 

Plate  VII. 
DESCRIPTION. 

Shell  suboval,  slightly  ventricose  anteriorly;  disk 
with  profound  oblique  undulations,  numerous  and  re- 
curved behind  the  umbonial  slope;  umbo  narrow, 
slightly  prominent,  oblique,  nearly  terminal;  ligament 
margin  elevated,  nearly  straight;  epidermis  yellowish 
brown,  sometimes  blackish  brown,  much  wrinkled 
posteriorly;  within  white,  iridescent  posteriorly, 
waved  on  the  margin;  cardinal  teeth  very  thick. 

SYNONYMES. 


U.  costatus,  Raf.     Ann.  gen.  des  Sc.  Phys.  vol.  v.  p.  49.  pi. 

lxxxii.  fig.  13,  14.   Poulson's  trans,  p.  57.    Say,  Amer.  Conch. 

No.  6.     Ferus.  Mag.  de  Zool. 
U.  undulate,  Barnes.     Silliman's  Journ.  vol.  vi.  p.  121,  pi.  2. 


OBSERVATIONS. 

This  shell  very  nearly  approaches  U.  plicatus,  Say, 
and  some  varieties  can  scarcely  be  distinguished 
from  it.  It  has,  in  general,  more  undulations,  a  much 
less  prominent  umbo,  is  less  ventricose,  and  has  often 
a  yellowish  epidermis,  which  is  not  the  case  with  the 
plicatus.  Not  uncommon  in  the  western  waters,  and 
in  the  Alabama  river;  very  large  and  fine  in  the 
rivers  of  Tennessee. 


18 

This  species  in  some  of  its  varieties  so  nearly  re- 
sembles U.  heros,  of  Say,  when  the  latter  is  old  and 
eroded  on  the  umbones,  that  Mr.  Say  at  one  time 
considered  them  identical;  the  young  shell  of  the  he- 
ros,  however,  was  found  to  be  so  entirely  dissimilar 
to  the  young  of  the  costatus,  that  the  specific  differ- 
ence was  obvious  to  the  most  careless  observer,  and 
Mr.  Say  in  his  synonymy  retains  his  species.  This 
circumstance  should  induce  those  naturalists  who 
live  in  favourable  situations  to  study  the  young  of 
every  species,  for  as  Mr.  Lea  has  justly  observed, 
they  are  the  most  certain  guides  to  specific  distinc- 
tions; when  the  umbones  and  beaks  are  perfect,  most 
species  will  exhibit  very  nearly  the  prominent  cha- 
racters of  the  very  young  shells,  and  hence  the  ne- 
cessity of  procuring  cabinet  specimens  of  the  most 
perfect  description,  if  we  would  effectually  trace  the 
species  and  make  ourselves  acquainted  with  their 
affinities. 


19 


UNIO  RETUSUS. 

Plate  VIII. 
DESCRIPTION. 

Shell  transversely  ovate,  ventricose,  with  concen- 
tric furrows;  umbo  very  prominent,  curved  forwards; 
beaks  retuse,  medial;  ligament  long  and  prominent; 
umbonial  slope  rounded,  undefined;  anterior  and  basal 
margins  regularly  rounded;  posterior  side  with  a 
slight  furrow,  and  emarginate  at  the  extremity;  liga- 
ment slope  arcuate,  very  oblique;  within  dark  purple, 
margined  with  white. 

SYNONYMES. 

U.  retusa,  Lam.     An.  sans  vert.  vol.  vi.  p.  72.     Ferus.     Mag. 

de  Zool. 
U.  torsa,  Raf.      Ann.  gen.  des  Sc.  Phys.  vol.  v.    p.  45.  pi. 

lxxxii.  fig.  1,  2,  3.     Poulson's  trans,  p.  40. 

OBSERVATIONS. 

This  fine  species  is  remarkable  for  the  elegance  of 
its  form,  and  the  prominent  curved  beaks  which 
somewhat  resemble  those  of  an  Isocardia.  The  colour 
of  the  nacre  is  remarkably  constant.  One  variety  is 
deeply  sulcated  and  emarginate  posteriorly;  another 
is  entire.  Young  shells  much  resemble  U.  subrotun- 
dus,  Raf.  Common  in  the  western  waters.  I  did 
not  observe  it  in  Alabama. 


20 


UNIO  PARVUS. 

Plate  IX. — Fig.  1. 
DESCRIPTION. 

Shell  oblong  or  elliptical,  with  prominent  concen- 
tric lines,  and  slightly  contracted  from  beak  to  base; 
inflated  posteriorly  and  the  basal  margin  dilated  and 
rather  abruptly  ascending  to  the  extremity,  which  is 
narrow,  obtuse,  and  much  above  the  line  of  the  base; 
umbo  when  not  decorticated,  profoundly  sulcated; 
umbonial  slope  undefined;  posterior  slope  with  a  sub- 
marginal,  slightly  prominent  line;  ligament  margin 
not  oblique;  posterior  margin  obliquely  truncated 
above;  within  white;  cardinal  teeth  very  erect. 

SYNONYMES. 

U.  parvus,  Barnes.     Silliman's  Journal,  vol.  vi.  p.  174. 
Cab.  A.  N.  S.  No.  1 872. 

OBSERVATIONS. 

A  small  species,  without  any  prominent  character, 
yet  very  distinct.  It  approaches  nearest  to  U.  lieno- 
sus,  nob.  but  that  species  is  always  more  or  less 
radiated  and  generally  pink  or  purple  in  the  interior; 
the  parvus  is  white  within  and  rarely  rayed.  Inhabits 
western  rivers  generally  from  Bayou  Teche  in  Louisi- 
ana to  Fox  river  in  the  North  Western  Territory. 

An  elegant  specimen  from  the  Scioto  river  is  dark 
olive-green  and  distinctly  rayed;  and  the  acutely  an- 
gulatcd  ridges  on  the  beaks  are  very  perfect. 


21 


UNIO  GLANS. 

Plate  IX. — Fig.  2. 
DESCRIPTION. 

Shell  ovate-elliptical,  thickened  anteriorly;  surface 
with  numerous  concentric  lines;  anterior  side  short; 
posterior  side  subcuneiform;  umbo  slightly  prominent; 
beaks  undulated;  umbonial  slope  undefined;  epidermis 
generally  dark  brown,  sometimes  rayed;  within  dark 
purple,  except  on  the  anterior  margin;  cardinal  teeth 
prominent,  direct. 

SYNONYMES. 

U.  glans,  Lea.     Trans.   Amer.  Philos.  Soc.  new  series,  vol.iv. 

pi.  viii.  fig.  12. 
Cab.  d.  N.  S.  No.  1168. 

OBSERVATIONS. 

This  does  not  appear  to  be  an  abundant  species, 
yet  it  is  occasionally  found  in  the  waters  of  Ohio, 
Tennessee  and  Alabama.  In  the  latter  state  I  met 
with  it  only  in  the  tributaries  of  the  Tennessee  river. 
The  purple  nacre  and  white  anterior  margin  will  al- 
ways distinguish  this  species  from  any  other,  which 
resembles  it  in  form.  Another  peculiarity  is  the 
posterior  tooth  of  the  left  valve  pointing  to  the  pos- 
terior extremity,  which  causes  the  teeth  to  diverge 
greatly.  It  most  resembles  U.  licnosus,  nob.  and  U. 
parvus,  Barnes.  The  figure  represents  the  largest 
and  best  specimen  I  have  seen,  and  the  only  one  that 
is  distinctly  rayed;  it  is  from  the  Harpeth  river, 
Tennessee. 


>)') 


UNIO  SILIQUOIDEUS. 

Plate  X.— Fig.  1. 
DESCRIPTION. 

Shell  ovate-oblong  or  elliptical,  ventricose,  mode- 
rately thick;  surface  glabrous,  olive-yellow,  with  nu- 
merous green  rays  varying  much  in  size;  anterior 
side  not  very  short,  margin  regularly  rounded;  liga- 
ment margin  straight,  not  declining;  posterior  ex- 
tremity angulated;  umbonial  slope  undefined;  beaks 
with  flexuous  undulations;  within  bluish-white;  cardi- 
nal teeth  oblique,  lateral  teeth  slightly  decurved  pos- 
teriorly. 

SYNONYMES. 

U.  siliquoideus,  Barnes.     Silliman's  Jourri.  vol.  vi.  p.  269. 
U.  inflatus,  lb.     p.  267. 
Cab.  A.  N.  S.  No.  1055. 

OBSERVATIONS. 

The  species  which  most  resembles  this  appears  to 
be  the  radiatus,  which  for  comparison  we  figure  upon 
the  same  plate.  Young  specimens  differ  constantly 
from  the  radiatus  in  having  a  straw-coloured  highly 
polished  epidermis,  and  much  undulated  beaks;  are 
more  inflated,  have  the  anterior  side  longer  and  the 
margin  more  regularly  rounded.  The  sexual  varie- 
ties arc  far  more  strongly  marked,  some  specimens 
having  almost  the  form  of  U.  cariosus,  whilst  the  ra- 
diatus offers  comparatively  slight  differences  of  out- 
line.   Old  shells  become  thick  and  much  inflated,  and 


23 

resemble  in  form  the  U.  teres,  Raf.  common  in  the 
western  rivers.     I  did  not  observe  it  in  Alabama. 

Mr.  Say,  in  his  synonymy  of  the  western  species, 
has  given  the  siliquoideus  as  a  synonyme  of  U.  cariosus, 
considering  it  a  mere  variety  of  that  species,  and 
more  strangely  merges  the  radiatus  in  the  same.  We 
have  seen  abundance  of  both  the  latter  and  cariosus, 
in  the  Schuylkill  and  Delaware,  but  never  any  varie- 
ties of  either  which  could  for  one  moment  have  led  us 
to  confound  the  two  species.  Mr.  Lea  informs  us 
that  a  specimen  of  the  siliquoideus  in  the  Garden  of 
Plants  at  Paris,  is  labelled  lutcola  of  Lamarck;  this 
name  we  should  have  adopted  if  Ferussac  had  not 
referred  Lamarck's  specimen  of  luteola  to  cariosus,  of 
Say,  which  we  presume  to  be  correct,  as  that  distin- 
guished naturalist  is  well  acquainted  with  those 
species  which  are  common  in  the  United  States. 

In  Bayou  Teche  there  occurs  a  beautiful  species 
allied  to  this  if  it  be  not  a  variety;  it  is  distinguished 
by  a  darker  epidermis,  with  distant  and  dark  green 
rays  of  nearly  uniform  size.  We  have  not  seen  many 
specimens,  but  a  figure  of  it  will  be  given  when  its 
characters  shall  be  determined  and  its  affinity  with 
the  siliquoideus  clearly  ascertained. 


24 


UNIO  RADIATUS. 

Plate  X.— Fig.  2. 
DESCRIPTION. 

Shell  oblong-ovate,  thin,  slightly  compressed  on 
the  anterior  side;  surface  with  fine  wrinkled  lines 
and  distinct  furrows;  olive,  with  numerous  green  rays, 
varying  in  size;  anterior  side  short  and  narrowed; 
margin  abruptly  rounded;  posterior  side  dilated;  liga- 
ment margin  elevated,  slightly  curved;  anterior  basal 
margin  slightly  contracted;  umbonial  slope  undefined; 
posterior  extremity  subtruncated;  within  yellowish  or 
salmon  coloured,  and  thickened  anteriorly;  bluish  and 
highly  iridescent  posteriorly. 

SYNONYMES. 

U.  radiata,  Lam.     An.  sans  vert.  vol.  vi.  p.  73. 

Barnes.     Silliman's  Journ.  vol.  vi.  p.  265. 

Mya  radiata,  Spengl.  Gmel. 

U.  virginiana,  Lam.     An.  sans.  vert.  vol.  vi.  p.  79. 

U.  oblongata,  Wood.     Suppl.  Index.  Test. 

Cab.  A.  N.  S.No.  1116. 

OBSERVATIONS. 

A  common  species  in  the  tide  waters  of  the  middle 
states,  and  very  abundant  in  those  of  Virginia,  but  it 
has  not  been  found  in  any  of  the  tributaries  of  the 
Mississippi,  except  the  Ouisconsin  river,  where, 
according  to  Mr.  Barnes,  it  was  obtained  by  Mr. 
Schoolcraft.  This  naturalist  remarks  that  it  inhabits 
Saratoga  lake. 


25 


UNIO  PECTOROSUS. 

Plate  XL— Fig.  1. 
DESCRIPTION. 

Shell  elliptical,  inflated,  moderately  thick,  yellow- 
ish or  olive,  with  unequal  green  rays,  the  larger  rays 
having  distant  dark  spots;  anterior  side  compressed, 
extremity  acutely  rounded;  ligament  margin  parallel 
with  the  base;  umbonial  slope  angular;  umbo  broad, 
prominent,  summit  obtusely  rounded;  beaks  distant 
from  the  anterior  extremity;  within  white,  with  a 
wide  greenish  margin;  cardinal  teeth  thick,  promi- 
nent, direct;  cardinal  plate  dilated. 

SYNONYME. 

IT.  pectorosus,  JVob.     New  fresh  water  shells,  p.  ST.  pi.  vi.  fig.  1. 

May,  1834. 
U.  perdix,  Lea.     Trans.  Ainer.  Philos.  Soc.  new  series,  vol.  v. 

p.  72.  pi.  xi.  fig.  51.  Sept.  1834. 
Cab.  A.  N.  S.  No.  2102. 

OBSERVATIONS. 

This  shell  has  so  nearly  the  outline  of  U.fascioh/s, 
that  I  have  figured  both  on  the  same  plate  for  com- 
parison. It  differs  from  that  species  in  the  rays, 
dilated  cardinal  plate,  &c.  It  is  allied  to  U.  ovutus, 
Say,  but  is  much  more  elongated.  The  specimen  re- 
presented has  double  cardinal  teeth  in  each  valve,  but 
the  character  is  not  permanent.  It  is  in  the  splendid 
collection  of  Mr.  Poulson,  and  was  found  in  the  Har- 
peth  river,  Tennessee.     I  obtained  a  few  specimens 

D 


§6 

on  the  bank  of  Elk  river,  Alabama,  in  which  the  epi- 
dermis was  dark  and  the  rays  obscure.  Mr.  Lea 
compares  it  with  the  crassus.  Say,  but  we  cannot 
find  any  point  of  resemblance. 


UNIO  FASCIOLUS. 

Plate  XL— Fig.  2. 
DESCRIPTION. 

Male.  Shell  elliptical,  inflated,  yellowish,  with  nu- 
merous unequal  flexuous  green  rays;  anterior  margin 
regularly,  not  obtusely  rounded;  posterior  extremity 
angulated;  ligament  margin  slightly  declining;  umbo 
wide,  prominent;  beaks  retuse,  distant  from  the  an- 
terior extremity;  umbonial  slope  obtusely  rounded; 
within  white;  cardinal  teeth  prominent,  diverging; 
margin  horn-coloured,  shewing  the  exterior  rays. 

Female.  Short  ovate;  posterior  side  dilated;  umbo 
narrower  and  more  oblique;  ligament  margin  elevated. 

SYNONYMES. 

U.  fasciolus.  Raf.  An.  gen  ties  Phys.  Sec.  vol.  5.  p.  Poul- 
son's  trans,  p.  28.     Say.     Amer.  Conch.  No.  6. 

U.  multiradiatus,  Lea.  Trans.  Amer.  Philos.  Soc.  new  series, 
vol.  3.  p.  48.  pi.  ix.  fig.  15. 

Cab.  A.  N.  S.  No.  1429. 

OBSERVATIONS. 

Distinguished  by  its  numerous  unequal  green 
Undulated  rays;  without  these  the  female  might  be 


27 

mistaken  for  U.  cariosus.  Old  shells  are  very  thick 
and  ponderous,  and  Mr.  Poulson  has  a  fine  specimen 
of  this  description.  Had  the  Baron  de  Ferussac  seen 
this,  we  think  he  would  not  for  a  moment  have  deemed 
it  a  variety  of  U.  subovatus.  Mr.  Phillips  has  two 
fine  specimens,  male  and  female;  the  former  is  repre- 
sented. 


UNIO  CONGARiEUS. 

Plate  XII.— Fig.  1. 

DESCRIPTION. 

Shell  elliptico-rhomboidal,  thin,  somewhat  flattened 
at  the  sides;  epidermis  olive  or  reddish-brown,  with 
numerous  green  rays,  sometimes  obsolete;  umbones 
flattened,  broad;  summits  obtusely  rounded,  slightly 
prominent;  umbonial  slope  profoundly  angulated; 
ligament  slope  slightly  oblique;  posterior  slope  much 
depressed,  with  oblique,  irregular,  undulated  lines; 
within  white,  highly  iridescent;  cardinal  teeth  oblique; 
lateral  teeth  elongated,  slightly  curved. 

SYNONYME. 

U.  congar;eus,  Lea.     Trans.  Amer.  Philos.  Soc.  new  series,  vol. 

4.  p.  72.  pi.  vi.  fig.  4. 
Cab.  A.  N.  S.No.  2101. 

OBSERVATIONS. 

Inhabits  the  eastern  waters  of  South  Carolina.  I 
found  it  also  at  Augusta,  Georgia,  in  great  numbers. 


28 

It  certainly  approaches  U.  ?iigcr,  Raf.;  the  young  of 
the  latter  resembling  it  so  much,  as  to  lead  to  the 
inference  that  they  may  be  varieties  of  one  species, 
occasioned  by  difference  of  locality.  Specimens  from 
Augusta  resemble  the  niger  more  than  those  from  the 
Congaree  river;  and  in  Flint  river,  Georgia,  is  a  va- 
riety of  the  latter,  differing  only  from  the  congarceus 
in  being  rather  larger  and  more  ponderous. 


UNIO  MASONI. 

Plate  XII.— Fig.  2. 

DESCRIPTION. 

Shell  suboval,  thin;  umbones  broad,  inflated,  disks 
slightly  flattened  near  the  umbonial  slope;  beaks  dis- 
tant from  the  anterior  margin;  ligament  margin  ele- 
vated; umbonial  slope  angulated;  epidermis  oliva- 
ceous, polished,  wrinkled  inferiorly;  summits  decor- 
ticated; within  white,  cardinal  teeth  oblique,  rather 
thick. 

SYNONYME. 

U.  masont,  Nob.     New  fresh  water  shells,  p.  34.  pi.  5.  fig.  2. 
Cab.  A.  2V.  <5'.  No.  2100. 

OBSERVATIONS. 

Inhabits  Savannah  river,  at  Augusta.  When  the 
description  was  originally  published,  1  had  seen  only 


29 

the  young  shell,  but  subsequently,  in  examining  a 
number  of  specimens  of  U.  congarceus  from  the  same 
locality,  an  adult  specimen  was  discovered,  which  has 
served  for  the  figure  and  description.  It  is  in  Mr. 
Phillips's  cabinet.  The  outline  of  the  young  shell  is 
represented  for  comparison  with  that  of  U.  congarceus. 
Mr.  Poulson's  cabinet. 

It  is  dedicated  to  Mr.  William  Mason,  whose  dis- 
coveries have  much  advanced  our  knowledge  of 
American  concholoav. 


UNIO  COCCINEUS. 

Plate  XIIL— Fig.  1. 

DESCRIPTION. 

Shell  oblique,  subtriangular,  compressed,  slightly 
waved;  epidermis  blackish-brown,  with  crowded 
wrinkles;  anterior  side  very  short;  posterior  side  sub- 
cuneiform,  much  compressed,  extremity  truncated; 
umbo  slightly  flattened;  basal  margin  not  much  ar- 
cuated posteriorly;  posterior  margin  slightly  sinuous, 
oblique,  rounded  above;  umbonial  slope  abruptly 
rounded;  summits  prominent,  eroded;  within  salmon 
colour,  rarely  white;  cardinal  teeth  double  in  each 
valve,  direct. 


SYNONYME, 


U.  coccineus,  Hildrcth. 
Cub.  A.  N.  S.  No.  2104. 


30 

OBSERVATIONS. 


This  shell,  in  having  a  slightly  undulated  disk,  ap- 
proaches the  mytiloides,  Raf.,but  is  very  distinct.  It 
is  well  known  in  the  collections  by  the  name  we  have 
adopted,  but  we  are  informed  that  Dr.  Hildreth  has 
not  published  his  description  of  it.  I  have  figured  a 
fine  specimen  from  Mr.  Hyde's  cabinet.  This  na- 
turalist observes  that  the  species  inhabits  Mahoning 
river,  near  Pittsburg,  and  that  of  the  very  many 
specimens  he  has  received,  none  has  perfect  beaks. 


UNIO  CATILLUS. 

Plate  XIII.— Fig.  2. 
DESCRIPTION. 


Shell  oval  orbicular,  slightly  oblique,  moderately 
thick,  convex,  dark  chestnut-brown,  with  crowded 
wrinkles;  anterior  margin  obtusely  rounded  or  sub- 
truncated;  posterior  margin  rectilinear,  nearly  direct, 
extremity  rounded;  umbonial  slope  rounded;  umbones 
inflated,  narrow,  prominent;  ligament  margin  rectili- 
near, oblique,  angular  posteriorly;  summits  slightly 
flattened;  beaks  much  incurved,  pointed,  slightly  tu- 
berculated;  lunule  short  ovate;  within  rosaceous; 
cardinal  teeth  thick,  direct,  profoundly  sulcated;  la- 
teral tooth  of  the  left  valve  very  thick,  that  of  the 
right  valve  compressed,  and  rising  from  a  very  broad 
plate  or  base  projecting  on  either  side;  cardinal  plate 
profoundly  dilated. 


Cab.  A.  X.  S.  Xo.  2103. 


31 

OBSERVATIONS. 

This  species  has  been  sent  from  the  west,  under 
the  name  of  coccincus,  but  is  so  very  distinct  that  I 
should  not  otherwise  have  compared  it  with  that 
species.  It  approaches  nearest  to  the  polltus  of  Say, 
and  obliquas,  Lam.,  but  the  peculiarity  of  the  teeth 
and  greatly  dilated  cardinal  plate,  as  well  as  many 
other  characters,  forbid  a  union  with  either.  Mr. 
Hyde  informs  me  that  a  great  number  of  specimens 
in  his  possession,  from  the  Scioto  river,  shew  the  in- 
terior to  be  generally  of  a  rose  colour  or  purple,  oc- 
casionally nearly  white,  and  rarely  salmon.  Of  the 
latter  Mr.  Hyde  possesses  a  specimen  more  beauti- 
fully coloured  than  any  Unio  I  have  seen — it  will  be 
figured  in  a  future  number.  The  figure  is  from  a 
specimen  in  the  cabinet  of  Mr.  Phillips. 


UNIO  PRODUCTUS. 

Plate  XIV.— Fig.  1. 

DESCRIPTION. 

Shell  narrow-elliptical,  produced,  moderately  thick, 
slightly  ventricose,  somewhat  contracted  near  the 
middle;  anterior  side  short,  dilated,  margin  obtusely 
rounded;  basal  margin  sinuous;  posterior  side  ros- 
trated; extremity  rounded,  much  above  the  line  of  the 
base;  ligament  margin  parallel  with  the  line  of  the 
base;  umbonial  slope  obtusely  carinated;  umbo  decor- 
ticated, not  elevated  above  the  dorsal  line;  within 


purplish;   cardinal  teeth  thick,  direct;   lateral  teeth 
thick. 

OBSERVATIONS. 

On  a  passing  glance  this  shell  would  certainly  be 
mistaken  for  U.  ?iasutus,  but  the  thickness  of  the  shell, 
the  dilated  anterior  side,  and  thick,  direct,  lateral 
teeth,  will  sufficiently  distinguish  it.  The  disk  pos- 
teriorly has  several  small  plicae  or  undulations  simi- 
lar to  those  of  U.  grayanus,  Lea,  but  as  only  one 
specimen  can  be  examined  this  character  may  prove 
inconstant. 

In  the  cabinet  of  Mr.  Phillips.  I  found  it  on  the 
shore  of  Savannah  river,  at  Augusta,  and  supposed 
it  to  be  a  variety  of  nasutiis,  but  comparing  it  with 
that  species  from  South  Carolina  and  Florida,  it  was 
found  to  differ  materially,  and  to  form  a  link  between 
it  and  the  rectus. 


UNIO  LANCEOLATUS. 

Plate  XIV.— Fig.  2. 

DESCRIPTION. 

Shell  narrow-elliptical,  thin,  ventricose,  yellowish, 
smooth  and  polished;  disks  slightly  flattened;  ante- 
rior side  somewhat  compressed,  not  very  short,  mar- 
gin regularly  rounded;  umbonial  slope  regularly 
rounded,  inflated;  posterior  side  produced,  extremity 


33 

angulated;  beaks  not  prominent;  ligament  margin 
short,  elevated;  within  pale  salmon  colour;  lateral 
teeth  slightly  recurved. 

SYNONYME. 

U.  lanceolatus,  Lea.     Trans.  Amer.  Philos.  Soc,  new  series, 

vol.  iii.  pi.  3.  fig.  2. 
Cab.  A.  N.  S.  No.  1105. 

OBSERVATIONS. 

Inhabits  Tar  river,  N.  C,  Mr.  Lea.  Mr.  Hyde 
has  received  specimens  from  the  Rappahannoc  at 
Fredericksburg,  Va.  It  approaches  nearest  in  out- 
line to  U.  productus  and  tiasiitus,  but  cannot  be  easily 
confounded  with  either. 


UNIO  RECTUS. 

Plate  XV. 
DESCRIPTION. 

Shell  profoundly  elongated,  thick;  anterior  side 
short;  posterior  side  rostrated,  cuneiform;  extremity 
angular,  compressed;  umbo  inflated,  but  not  promi- 
nent, obtusely  rounded;  disks  slightly  contracted  in 
the  middle;  ligament  margin  nearly  rectilinear;  epi- 
dermis dark  green  or  olive-brown,  smooth,  frequently 
with  broad  green  rays;  within  pink  in  the  middle; 
cardinal  teeth  small,  direct,  double  in  each  valve. 

SYNONYMES. 

U.  rectus,  Lam.     An.  sans  vert.  vol.  vi.  p.  74. 
E 


34 

U.  latissima,  Raf.     An.  gen.  des  Sc.  Phys.  vol.  5.  p.  31.     Poul- 

son's  trans,  p.  25. 
U.  pr^longus,  Barnes.     Silliman's  Jour.  vol.  vi.  p.  261. 
Cab.  A.  N.  S.No.  1112. 

OBSERVATIONS. 

This  shell  resembles  in  outline  U.  nasutus,  Say,  U. 
la?iceolatus,  Lea,  and  U.  teres,  Raf.  With  the  latter 
it  has  most  affinity.  It  is  a  common  western  species, 
found  as  far  north  as  the  Ouisconsin,  and  inhabits 
the  Alabama  river  near  Claiborne.  The  figure  was 
taken  from  a  fine  male  specimen  in  Mr.  Poulson's 
cabinet. 


UNIO  CRASSUS. 

Plate  XVI. 
DESCRIPTION. 

Male.  Shell  ovate,  thick,  yellowish,  with  brown 
rays,  obsolete  inferiorly;  umbo  broad,  flattened;  beaks 
obtuse,  nearly  terminal;  umbonial  slope  angulated; 
posterior  side  cuneiform;  posterior  dorsal  margin 
arcuate;  basal  margin  dilated  behind  the  middle;  pos- 
terior extremity  angular;  within  salmon  colour  or 
white,  with  a  horn-coloured  margin;  cardinal  teeth 
direct,  thick,  very  prominent,  subtrifid. 

Female.  Shell  oval  quadrate,  ventricose,  posterior 
side  dilated;  posterior  margin  widely  truncated,  di- 
rect; umbo  oblique  and  terminal. 


35 

SYNONYMES. 

U.  crassus,  Say.     Nich.  Enc.  (Amer.  ed.)  art.  Conch,  pi.  i.  tig. 

8.  old  male. 
U.  crassidens,  var.  c.  Lam.     An.  sans  vert.  vol.  vi.  p.  71. 

U.  LIGAMENTINA,  ib.  p.  72. 

U.  ellipticus,  Barnes.     Silliman's  Jour.  vol.  vi.  p.  259.  male. 
U.  suborbiculatus,  Hildreth.     Silliman's  Jour.  vol.  xiv.  female. 
U.  abruptus,  Say.     Amer.  Conch,  pi.  17,  female,  var.  A.  male. 
U.  cyclops,  Eaf.    Contin.  of  Monog.  p.  2,  female. 
Cab.  A.  N.  S.  No.  358. 

OBSERVATIONS. 

Closely  related  to  U.fascialus,  Raf.,  but  can  be  dis- 
tinguished from  that  species  by  fewer  and  narrower 
rays,  generally  distinct  only  over  the  umbones;  by  a 
lighter  coloured  more  polished  epidermis;  more  pro- 
minent teeth,  and  the  prevalence  of  a  salmon  co- 
loured interior.  Common  in  the  rivers  of  Ohio, 
Indiana,  and  Illinois,  but  appears  to  be  rare  in  the 
more  southern  states.  I  could  not  find  it  in  the 
rivers  of  Alabama.  The  specimen  figured  was  pre- 
sented by  Dr.  Blanding. 


UNIO  VIRIDIS. 

Plate  XVII.— Fig.  1. 

DESCRIPTION. 


Shell  elliptical  or  subovate,  ventricose,  thin;  disks 
slightly  flattened  anteriorly,  much  inflated  over  the 
umbonial  slope;  lines  of  growth  prominent;  ligament 
margin  elevated;  posterior  slope  dilated;  posterior 


36 

extremity  truncated,  direct;  epidermis  with  green 
ray  s,  obsolete  anteriorly,  distinct  and  very  unequal 
posteriorly;  umbo  slightly  prominent;  beaks  with  an- 
gular furrows,  pointed;  within  white,  iridescent;  car- 
dinal teeth  compressed,  oblique,  that  of  the  left  valve 
double  or  trifid;  lateral  teeth  of  the  left  valve  imper- 
fectly divided. 

SYNONYME. 

U.  viridis,  Raf.     An.  gen.  des  Sc.  Phys.  vol.  v.  p.  2.7.   Poulson's 

trans,  p.  19. 
Cab.  A.  N.  S.  No.  2105. 

OBSERVATIONS. 

The  first  specimen  of  this  species  which  came 
under  my  observation,  was  found  in  the  Schuylkill 
river,  near  Philadelphia,  by  Mr.  Hyde,  who  kindly 
offered  me  the  use  of  it,  as  I  supposed  it  to  be  unde- 
scribed.  Comparing  it,  however,  with  a  single  valve 
from  the  Kentucky  river,  in  Mr.  Poulson's  cabinet, 
it  proved  to  be  of  the  same  species  with  that  speci- 
men which  was  labelled  viridis  by  Rafinesque.  Mr. 
Hyde  has  received  specimens  from  a  small  stream 
near  Lancaster,  and  from  the  Juniata  river.  One 
from  the  latter  locality  has  been  selected  for  the  figure 
and  description.  It  is  allied  to  U.  heterodon,  but  can- 
not be  confounded  with  that  species. 


37 


UNIO  OCHRACEUS. 

Plate  XVII.— Fig.  2. 

DESCRIPTION. 

Shell  elliptical,  inflated,  thin;  epidermis  smooth 
and  polished,  rugose  posteriorly,  yellowish,  with  nar- 
row green  unequal  rays;  anterior  side  narrowed,  and 
the  superior  margin  elevated  and  connate;  ligament 
margin  not  oblique;  umbo  inflated;  posterior  extre- 
mity angular;  umbonial  slope  angular;  basal  margin 
profoundly  arcuate;  within  white,  rarely  pale  rose  or 
salmon;  cardinal  teeth  very  oblique,  much  compressed, 
bifid  in  the  right  valve;  single  or  imperfectly  divided 
in  the  left;  lateral  teeth  arcuate. 

Var.  A.  Reddish  brown;  rays  obsolete  or  want- 
ing; within  rosaceous. 

SYNONYMES. 
U.  ochraceus,  Say.     Nich.  Enc.  (Amer.  ed.)  art.  Conch,  pi.  ii. 

Symphynota  ochracea,  Lea.     Trans.  Amer.  Philos.  Soc,  new 

series,  vol.  iii.  p.  69. 
Var.  A.  Mytilus  fluviatilis,  Gmel.     Lister,  tab.  157.  fig.  12. 
Cab.  A.  N.  S.  No.  1063. 

OBSERVATIONS. 

Very  common  in  the  Schuylkill  and  Delaware 
rivers,  and  inhabits  most  tide  waters  north  of  Savan- 
nah river.  Variety  A.  is  very  abundant  in  James 
river,  Virginia,  where  I  found  vast  numbers  of  shells 
brought  ashore  by  .seines  used  in  the  shad  fishery  in 


38 

the  month  of  March.  So  accurately  does  the  above 
mentioned  variety  agree  with  Lister's  figure  and  de- 
scription, that  I  cannot  doubt  the  identity.  The 
species  is,  perhaps,  most  closely  allied  to  II.  cariosus, 
its  common  associate  in  the  Delaware  and  Schuylkill. 
The  specimen  figured  has  a  double  cardinal  tooth  in 
each  valve. 


UNIO  NASUTUS. 

Plate  XVIIL— Fig.  1. 

DESCRIPTION. 

Shell  elongated,  compressed,  thin;  disks  slightly 
flattened;  anterior  side  short;  posterior  side  rostrated, 
tapering,  angular  at  the  extremity;  umbo  not  promi- 
nent; beaks  small,  eroded;  umbonial  slope  profoundly 
oblique,  angulated;  ligament  margin  rectilinear,  ele- 
vated; posterior  superior  margin  profoundly  oblique 
and  slightly  concave;  within  bluish,  iridescent,  rarely 
purple  or  salmon;  cardinal  teeth  compressed  and 
oblique,  double  in  each  valve. 

SYNONYMES. 

U.  nasutus,  Say.     Nich.  Enc.  (Amer.  ed.)  art.  Conch,  pi.  iv. 

fig.l. 
U.  rostrata,  Vcdenc. 
Lister,  tab.  151.  fig.  6. 
Cab.  A.  N.  S.  No.  1123. 

OBSERVATIONS. 

A  common  species  in  the  tide  waters  from  Florida 


39 

to  the  eastern  states.  I  found  it  in  great  abundance 
in  the  Potomac  river,  near  Washington,  where  the 
specimens  are  exceedingly  elongated.  The  smaller 
specimen  figured  is  a  female  variety  from  James 
river,  Virginia,  where  they  are  generally  ornamented 
with  rays;  the  other  figure  represents  a  rare  purple 
variety  from  Chester  river,  Maryland:  it  is  in  the 
cabinet  of  Mr.  Phillips.  In  old  shells  the  teeth  are 
often  thick  and  direct. 


UNIO  ICTERINUS. 

Plate  XVIII.— Fig.  2. 

DESCRIPTION. 

Shell  elliptical,  moderately  thick;  anterior  margin 
regularly  rounded;  posterior  margin  descending  ob- 
liquely, and  subtruncated  at  the  extremity;  umbo  not 
prominent;  summit  decorticated;  umbonial  slope  very 
oblique,  angulated;  epidermis  smooth  and  polished, 
olive  yellow;  within  salmon  coloured;  cardinal  tooth 
in  the  left  valve  trifid,  in  the  right,  single. 

SYNONYME. 

U.  icterinus,  Nob.     New  fresh  water  shells,  p.  41.  pi.  vi.  fig.  5. 
Cab.  Ji.  N.  S.  No.  2106. 

OBSERVATIONS. 

I  found  the  species  in  the  Savannah  river,  at  Au- 
gusta. It  resembles  U.  lanceolatus  in  epidermis  and 
colour.  Its  proper  place,  we  think,  is  between  nasn- 
tus  and  declivis^  Say. 


40 


UNIO  CARIOSUS. 

Plate  XIX. 
DESCRIPTION. 

Shell  subovate,  ventricose,  thick  anteriorly;  epider- 
mis yellowish  or  straw  coloured,  very  smooth  and 
polished,  with  a  few  narrow  dark  green  rays  poste- 
riorly, more  numerous  on  the  posterior  slope;  umbo 
prominent,  decorticated;  umbonial  slope  angulated; 
ligament  margin  elevated;  ligament  prominent;  basal 
margin  swelling  posteriorly;  within  white;  cardinal 
teeth  double  in  each  valve,  prominent,  oblique. 

SYNONYMES. 

U.  cariosus,  Say.     Nich.  Enc.  (Amer.  ed.)  art.  Conch,  pi.  iii. 

fig.  Q.  female. 
U.  ltjteola,  Lam.     An.  sans  vert.  vol.  vi.  p.  79. 
U.  ovatus,  Valenc. 
Cab.  A.  N.  S.  No.  1022. 

OBSERVATIONS. 

This  is  one  of  the  most  abundant  species  in  the 
tide  waters  of  the  middle  states,  but  I  found  it  com- 
paratively rare  in  the  Potomac  and  James  rivers.  In 
varieties  of  form  it  much  resembles  U.  crassus,  and 
both  male  and  female  are  represented,  in  order  to 
convey  a  clear  idea  of  sexual  differences,  which  are 
so  striking  in  a  large  proportion  of  the  species.  It 
is  very  often  destitute  of  rays,  and  I  have  seen  only 
one  specimen  in  which  the  rays  extended  over  the 
disk  to  the  anterior  margin. 


41 
UNIO  MYTILOIDES. 

Plate  XX. 
DESCRIPTION. 

Shell  elevated,  subtriangular;  epidermis  reddish- 
brown,  with  crowded  wrinkles;  posterior  side  with  a 
broad  furrow;  anterior  side  gibbous;  umbo  tapering, 
curved,  narrowed  at  the  summit,  which  is  much  ele- 
vated; lunule  obtusely  cordate;  within  white,  purple, 
and  iridescent  towards  the  posterior  extremity;  car- 
dinal teeth  large,  very  thick,  prominent,  sulcated; 
posterior  muscular  impressions  impressed,  the  smaller 
one  profoundly. 

SYNONYMES. 

U.  mytiloides,  Raf.    Ann.  gen.  des  Sc.  Phys.  vol.  v.  p.  47.  pi.  82. 

fig.  8.     Poulson's  trans,  p.  53. 
U.  rubra,  Raf. 
U.  pyramidatus,  Lea.     Trans.  Ainer.  Philos.  Soc,  new  series, 

vol.  iv.  p.  109,  pi.  xvi.  fig.  39. 
U.  caridiacea,  Say  of  Guerin. 
Cab.  A.  N.  S.  No.  2017. 

OBSERVATIONS. 

This  common  species,  since  its  first  discovery  in 
the  western  waters,  has  always  been  known  by  the 
name  we  have  adopted.  It  is  nearly  allied  to  U.  cor, 
Nob.,  and  II.  undalus,  Barnes,  but  is  very  distinct, 
although  its  varieties  are  intricate  and  perplexing. 
Young  specimens  are  very  short  and  greatly  elevated, 
and  frequently  rayed;  old  shells  are  compressed,  cu- 


42 

neiform,  and  produced  posteriorly;  the  rays  confined 
to  the  umbo  and  obsolete.  Inhabits  the  Alabama 
and  Black  Warrior  rivers. 


UNIO  DILATATUS. 

Plate  XXI. 
DESCRIPTION. 

Shell  ovato-elliptical,  thick  and  ponderous,  slightly 
sinuous;  posterior  side  produced,  compressed,  cunei- 
form; umbo  broad,  flattened,  summit  obtusely  round- 
ed; anterior  lunule  large,  elliptical;  umbonial  slope 
angulated,  not  very  distant  from  the  margin;  basal 
margin  slightly  contracted  near  the  middle;  within 
obliquely  sulcated  from  the  umbo  towards  the  poste- 
rior basal  margin;  colour  purple,  with  a  bluish  mar- 
gin; cardinal  teeth  thick,  direct;  lateral  teeth  very 
thick,  and  terminating  rather  abruptly. 

SYNONYMES. 

U.  dilatatus,  Raf.  Ann.  gen.  des  Sc.  Phys.  vol.  v.  p.  31.  Poul- 
son's  trans,  p.  25.  Say,  Amer.  Conch.  No.  6.  Ferr.  Mag.  de 
Zool. 

U.  nasutus,  Lam.     An.  sans  vert.  vol.  vi.  p.  75. 

U.  gibbosus,  Barnes.     Silliman's  Journ.  vol.  vi.  p.  262. 

Cab.  A.  IS.  S.  No.  1072. 

OBSERVATIONS. 

In  outline  this  species  approaches  U.  fasciolaris, 
but  "differs  in  the  much  less  dilated  cardinal  plate,  in 
having  the  anterior  [posterior]  smaller  muscular  im- 


43 

pression  situated  immediately  beneath  the  tip  of  the 
lamelliform  teeth,  in  having  the  anterior  [posterior] 
lunule  much  more  depressed,  with  slightly  elevated 
lines  crossing  the  wrinkles."*  It  also  differs  in  hav- 
ing a  purple  interior,  varying  from  an  intense  shade 
of  that  colour,  approaching  an  indigo  blue,  to  a  pale 
reddish-purple.  The  great  thickness  of  the  superior 
portion  of  the  shell  causes  the  cavity  of  the  umbo  to 
be  very  shallow. 

Common  in  the  tributaries  of  the  Ohio,  Upper 
Mississippi,  and  Missouri.  In  Alabama,  I  found  it 
only  in  the  Tennessee  and  its  tributaries.  It  is  a 
common  species  in  the  mountainous  region  of  North 
Carolina  and  Virginia,  where,  from  a  poverty  of  cal- 
careous matter,  it  is  always  comparatively  small. 
U.  cuprea  and  U.  atroviolacea,  Raf.,  appear  from  the 
descriptions  to  be  mere  varieties  of  if.  dilatatus. 


UNIO  TUBERCULATUS. 

Plate  XXII. 
DESCRIPTION. 

Shell  subquadrangular,  convex,  thick;  disk  covered 
with  irregular  tubercles,  except  towards  the  anterior 
margin;  tubercles  largest  near  the  centre  of  the  disk; 
anterior  margin  obtusely  rounded;  posterior  margin 
direct,  emarginate;  anterior  lunule  elliptical,  profound; 
umbo  narrow,  very  prominent;  beaks  pointed,  ap- 
proximate, but  generally  eroded  or  worn  in  maturity; 

*  Say.  Amer.  Conch,  pi.  22. 


44 

umbonial  slope  angulated;  basal  margin  arcuate;  epi- 
dermis green  olive,  with  green  capillary  rays  over 
the  umbo;  within  chocolate  colour;  cardinal  teeth 
very  large,  direct,  prominent,  trifid  in  the  right  valve; 
cavity  of  the  beak  very  profound. 

SYNONYMES. 

U.  tuberculatus,  Raf.     Ann.  gen.  ties  Sc.  Phys.  vol.  v.  p.  42. 

Say.  Avner.  Conch.  No.  G.     Ferr.  Mag.  de  Zool. 
U.  verrucosus,  Barnes.     Silliman's  Journ.  vol.  vi.  p.  125,  pi.  5, 

fig.  6. 
U.  tuberculosa,  Valeric. 
Cab.  A.  N.  S.  No.  1430. 

OBSERVATIONS. 

Some  varieties  of  this  species  closely  resemble  U. 
bullatas  exteriorly,  but  independent  of  other  charac- 
ters, the  chocolate  coloured  interior,  which,  though 
sometimes  pale,  never  wholly  disappears,  will  at  once 
distinguish  the  present  species  from  all  its  congeners. 
It  is  a  very  variable  shell;  some  specimens  from  the 
Harpeth  river,  Tennessee,  being  much  dilated  and 
compressed,  and  the  ligament  margin  so  much  ele- 
vated as  to  give  the  posterior  side  an  alated  appear- 
ance. Other  specimens  are  far  more  elevated  in 
proportion  to  their  length,  and  the  posterior  sulcus 
and  emargination  profound.  These  great  differences 
may  be  sexual  characters,  but  require  an  anatomical 
investigation  of  the  animal  to  settle  that  point. 

Common  in  the  western  rivers,  and  inhabits  Lake 
Erie  and  the  Ouisconsin,  according  to  Mr.  Barnes. 
It  is  not  found  in  Alabama  south  of  the  Tennessee 
river  and  its  tributaries. 


45 
UNIO  DECLIVIS. 

Plate  XXIIL— Fig.  1. 

DESCRIPTION. 

Shell  trapezoidal,  moderately  thick;  anterior  mar- 
gin obtusely  rounded;  beaks  slightly  elevated,  with 
oblique  undulations;  hinge  margin  rather  elevated 
and  compressed,  angulated  at  tip;  posterior  margin 
rectilinear,  descending  obliquely  to  a  prominent  ros- 
trum of  the  posterior  basal  margin  at  the  extremity  of 
the  umbonial  slope;  umbonial  slope  abruptly  rounded, 
and  bounded  on  its  posterior  side  by  two  slightly  im- 
pressed lines;  basal  margin  arcuate;  surface  deeply 
wrinkled;  within  tinged  with  purplish;  cardinal  teeth 
oblique;  lateral  teeth  distant  from  the  cardinal  teeth. 

SYNONYMES. 

U.  declivis,  Say.     Trans.  Journ.  vol.  iv.  p.  527",  Amer.  Conch. 

pi.  35. 
U.  geometricus,  Lea.     Trans.  Amer.  Philos.   Soc.  new  series, 

vol.  v.  p.  38,  pi.  4,  fig.  10. 
Cab.  Jl.  N.  S.  No.  1875. 

OBSERVATIONS. 

This  species  resembles  a  variety  of  the  comphnatus 
in  its  general  form,  and  its  teeth  and  posterior  angle 
are  somewhat  similar  to  those  of  nasuius.  It  is  very 
distinct  from  either.  The  figure  is  from  a  fine  speci- 
men which  I  found  in  a  small  creek  in  Greene  county, 
Alabama,  where  the  species  is  abundant,  but  usually 
more  compressed  than  the  one  I  have  selected  for 
representation.     I  was  unable  to  find  a  specimen  in 


46 

any  of  the  large  rivers.  It  is  common  in  Bayou 
Teche,  Louisiana,  and  has  been  found  in  the  Ohio 
canal  near  Louisville,  whence  Mr.  Hyde  has  received 
it. 


UNIO  BLANDINGIANUS. 

Plate  XXIIL— Fig.  2. 

DESCRIPTION. 

Shell  subtrapezoidal,  rather  thin,  ventricose;  ante- 
rior margin  very  obtusely  rounded;  ligament  margin 
much  elevated,  slightly  arcuate,  angulated  at  tip,  pos- 
terior margin  long,  oblique  and  rectilinear;  extremity 
subtruncated  or  obtusely  rounded;  beaks  slightly  ele- 
vated, eroded;  umbonial  slope  rounded,  very  distant 
from  the  margin;  epidermis  finely  wrinkled;  within 
purplish,  with  green  stains;  cardinal  teeth  small,  single 
in  the  right  valve  and  compressed;  widely  bifid,  and 
rather  obtuse  in  the  left;  lateral  teeth  distant  from 
the  cardinal  teeth,  and  arcuate;  anterior  muscular 
impressions  marginal. 

SYNONYME. 

U.  blandingianus,  Lea.     Trans.  Amer.  Philos.  Soc.  new  series, 

vol.  v.  p.  101,  pi.  xv.  fig.  44. 
Cab.  A.  N.  S.  No.  1859. 

OBSERVATIONS. 

A  species  allied  to  complanatus  and  declivis,  but 
differing  from  both  in  the  elevated  ligament  margin 
and  inflated  disks.     The  anterior  lunule  resembles 


47 


that  of  the  preceding  species.  It  was  obtained  in 
East  Florida,  from  an  Indian,  by  Dr.  Blanding,  and 
to  this  worthy  naturalist  the  species  has  been  pro- 
perly dedicated. 


UNIO  PERSONATUS. 

Plate  XXIV. 
DESCRIPTION. 

Shell  sublenticular;  length  rather  more  than  the 
height;  anterior  margin  forming  with  the  basal  mar- 
gin a  regular  curve  to  the  termination  of  the  umbo- 
nial  slope;  posterior  side  narrowed;  posterior  margin 
subtruncated;  umbo  rounded,  very  prominent,  subme- 
dial;  umbonial  slope  swelling  near  the  base,  gaping 
and  denticulate  on  the  margin;  epidermis  with  nu- 
merous capillary  rays,  profound  and  undulated  on 
the  posterior  side;  within  pink;  cardinal  teeth  direct, 
thick,  prominent;  lateral  teeth  slightly  recurved;  cavity 
of  the  beak  not  profound. 

SYNONYMES. 

U.  personatus,  Say.    New  Harmony  Disseminator,  p.  309,  1829. 
U.  capillaris,  Lea.     Trans.  Amer.  Philos.  Soc.  new  series,  vol. 

v.  p.  29,  pi.  2,  fig.  2,  1832. 
Cab.  A.  N.  S.  No.  1382. 

OBSERVATIONS. 

It  would  seem  from  the  observations  of  Dr.  Kirt- 
land,  that  all  those  Uniones  which  have  the  peculiar 
denticulated  and  dilated  base,  are  female  shells;  and 


48 

if  so,  we  are  unacquainted  with  the  male  pcrsonatus. 
The  exterior  somewhat  resembles  V.  Itevigatus,  and 
the  cardinal  teeth  are  very  like  those  of  U.  nexus; 
Say's  description  applies  only  to  the  immature  shell. 
For  the  use  of  the  splendid  specimen  here  represented 
and  described,  we  are  indebted  to  G.  W.  Feather- 
stonhaugh,  Esq.,  who  procured  it  from  Cumberland 
river,  Tennessee.  Mr.  Say's  specimens  were  from 
the  Wabash. 


UNIO  CORDATUS. 

Plate  XXV. 
DESCRIPTION. 

Shell  subtriangular,  not  oblique,  length  and  height 
nearly  equal;  beaks  distant  from  the  anterior  margin, 
prominent,  incurved  and  pointed;  anterior  lunule  very 
broad  and  obtusely  obovate,  beneath  which  is  a  flat- 
tened cordate  space  with  the  opposite  margin  recti- 
linear; inferior  portion  of  the  anterior  margin  regu- 
larly rounded  to  the  middle  of  the  basal  margin, 
which  is  emarginate  and  ascending  posteriorly;  sinus 
of  the  posterior  side  not  oblique,  slightly  arcuate; 
posterior  margin  rounded  above,  angulated  at  its 
junction  with  the  basal  margin;  epidermis  fuscous, 
with  green  interrupted  rays  over  the  umbo;  within 
white. 

SYNONYME. 

U.  cordatus,  liuf.    Ann.  gen.  des  Sc.  Phys.  vol.  v.  p.  46.    Poul- 

son's  trans,  p.  52. 
Cab.  A.  N.  6'.  No.  2018. 


49 

OBSERVATIONS. 

I  formerly  supposed  this  shell  a  variety  of  mijti- 
loldes,  but  the  differences  are  so  constant  in  a  great 
number  of  specimens,  that  it  may  be  useful  to  intro- 
duce it  to  conchologists  by  the  name  which  Rafinesque 
has  bestowed  upon  it.  It  differs  from  mytiloidcs  in 
not  being  oblique,  in  being  about  as  long  as  it  is  high, 
in  having  the  beaks  distant  from  the  anterior  margin, 
and  never  in  any  stage  of  growth  having  the  poste- 
rior side  prolonged  obliquely  downwards. 

Inhabits  the  Ohio  and  its  tributaries.  The  speci- 
men figured  belongs  to  the  cabinet  of  Mr.  Feather- 
stonhaugh,  and  is  from  Cumberland  river,  Tennessee. 
It  connects  U.  mytiloides  with  U.  undatus. 


UNIO  NIGER. 

Plate  XXVI. 

DESCRIPTION. 

Shell  elliptical;  with  age,  subovate,  or  subtriangu- 
lar;  thick  and  ponderous;  disks  somewhat  flattened; 
posterior  lunule  with  short,  oblique,  vermicular  raised 
lines;  posterior  side  compressed,  cuneiform;  umbo 
broad,  flattened,  summit  obtusely  rounded;  umbonial 
slope  angulated;  epidermis  reddish-brown,  frequently 
rayed;  within  purple  or  salmon  colour;  cardinal  teeth 
direct,  prominent;  lateral  teeth  thick,  distant  from 
the  cardinal  teeth;  posterior  muscular  impression 
slightly  impressed;  cavity  of  the  beak  shallow. 

G 


50 

SYNONYMES. 

U.  niger,  Raf.  Ann.  gen.  des  Sc.  Phys.  vol.  v.  p.  25.  Poul- 
son's  trans,  p.  15.  Say.  Amer.  Conch.  No.  6.  Ferr.  Mag.  de 
Zool. 

U.  crassidexs,  var.  b.  Lam. 

U.  cuneatus,  Barnes.     Silliman's  Journ.  vol.  vi.  p.  263. 

Cab.  A.  N.  S.  No.  2400,  2401,  2402. 

OBSERVATIONS. 

In  the  observations  on  U.  congarazus,  I  compared 
that  species  with  the  niger,  but  however  the  young 
of  both  may  resemble  each  other  exteriorly,  the  car- 
dinal teeth  of  the  latter  are  always  more  robust  and 
less  oblique,  and  the  interior  very  often  dark  purple, 
which  is  never  the  case  with  the  congarceus.  It  dif- 
fers most  obviously  from  II.  dilatatus,  in  being  com- 
paratively much  shorter,  and  in  the  raised  lines  on 
the  posterior  lunule. 

Common  in  the  western  streams,  and  very  abun- 
dant in  the  Black  Warrior  and  Alabama  rivers.  In 
Detroit  river,  Michigan,  it  has  been  obtained  by  Dr. 
Sager. 


UNIO  GIBBOSUS. 

Plate  XXVII.— Fig.  1. 

DESCRIPTION. 


Shell  subovate,  oblique,  with  a  submedial  nodulous 
ridge  projecting  at  base;  concentric  sulci  very  dis- 
tinct; posterior  side  with  a  wide  furrow;  umbonial 
slope  angulatcd;  umbo  prominent;  posterior  end  and 


51 

posterior  basal  margin  emarginate;  epidermis  smooth, 
shining,  yellowish  with  numerous  green  rays;  within 
white,  rarely  rose  coloured. 

SYNONYMES. 

U.  gibbosus,  Raf.     Ann.  gen.  des  Sc.  Phjs.  vol.  v.  p.  49.    Poul- 

son's  trans,  p.  56. 
U.  torulosus,  Raf.     lb.  p.  48.     Poulson's  trans,  p.  56. 
U.  perplexus,  Lea.     Trans.  Amer.  Philos.  Soc.  new  series,  vol. 

iv.  p.  122,  pi.  17,  fig.  42. 
Cab.  A.  N.  S.  No.  1051. 

OBSERVATIONS. 

Besides  its  affinity  with  the  preceding  species,  this 
shell  has  a  general  resemblance  to  three  others,  with 
none  of  which,  however,  can  it  be  confounded  by 
those  who  are  familiar  with  the  subject;  these  are 
U.jlexuosus,  U.  Phinipsii,  and  U.  refiexus. 

Common  in  the  Wabash  and  Scioto,  and  I  have 
found  it  in  the  Tennessee  river,  at  Florence,  Alabama, 
but  not  farther  south.  The  female  may  be  readily 
distinguished  by  the  dilated  margin,  which  is  more 
profound  in  this  species  than  in  any  other. 


UNIO  GIBBOSUS. 

VARIETY   PEROBLiaUUS. 
Plate  XXVII.— Fig.  2. 

OBSERVATIONS. 

This  is  perhaps  a  mere  variety  of  U.  gibbosus,  Raf., 
but  it  is  much  more  oblique,  the  beaks  nearer  the 


52 

anterior  extremity,  the  posterior  basal  emargination 
much  less  profound,  and  the  central  tubercles  are 
obsolete;  in  outline  it  closely  resembles  U.  obliquatus, 
but  that  species  is  always  of  a  purple  colour  within, 
though  the  tint  is  sometimes  pale. 

Inhabits  the  Wabash  river,  Indiana,  and  Detroit 
river,  Michigan. 


UNIO  TERES. 

Plate  XXVIII. 

DESCRIPTION. 

Shell  narrow — elliptical,  subcylindrical,  moderately 
thick;  umbo  slightly  prominent;  summit  obtusely 
rounded;  umbonial  slope  abruptly  rounded,  submar- 
ginal;  posterior  side  produced,  cuneiform;  epidermis 
yellowish  and  polished,  rarely  rayed;  within  white  or 
pale  salmon  colour;  cardinal  teeth  double  in  each 
valve,  subcompressed,  very  erect;  lateral  teeth  distant 
from  the  cardinal  teeth. 

SYNONYMES. 

U.  teres,  Raf.     Ann.  gen.  des  Sc.  Phys.  vol.  v.  p.  55.    Poulson's 

trans,  p.  68. 
U.  anodontoides,  Lea.     Trans.  Amer.  Philos.  Soc,  new  series, 

vol.  iv.  p.  91,  pi.  viii.  fig.  11. 
Cab.  A.  N.  S.  No.  1383. 

OBSERVATIONS. 

A  well  characterized  species,  approaching  the  rec- 
tus in  outline,  but  is  comparatively  shorter  and  emi- 


53 

nently  distinguished  by  the  peculiarity  of  its  pale 
epidermis.  The  sexes  are  well  marked  by  difference 
of  outline. 

Not  uncommon  in  the  Western  rivers,  and  in  Bayou 
Teche,  Louisiana,  where  it  is  ornamented  with  pale 
green  rays.  In  the  Alabama  river  it  is  partial  to  a 
muddy  bed,  and  rare  on  the  bars. 

I  have  figured  a  specimen  in  Mr.  Poulson's  cabinet, 
brought  from  the  west  and  labelled  by  Rafinesque. 


UNIO  SAGERI. 

Plate  XXIX.— Fig.  1. 

DESCRIPTION. 

Shell  narrow — elliptical,  moderately  thick  on  the 
anterior  and  thin  on  the  posterior  side;  disks  slightly 
contracted  from  beak  to  base,  causing  the  basal  mar- 
gin to  be  slightly  sinuous;  anterior  side  short,  margin 
regularly  rounded;  posterior  side  produced,  somewhat 
pointed,  extremely  obtuse;  ligament  margin  elevated; 
umbo  not  prominent,  flattened;  umbonial  slope  round- 
ed; within  bluish-white  and  iridescent;  cardinal  tooth 
in  the  ri^ht  valve  thick,  direct,  divided  at  the  summit 
by  a  deep  groove;  in  the  left  valve  widely  bifid,  with 
a  submedial  lamelliform  elevation;  lateral  teeth  com- 
pressed. 

OBSERVATIONS. 

This  interesting  species  was  found  in  Detroit  river, 
Michigan,  by  Dr.  Abraham  Sager,  of  Detroit,  to  whom 


54 

I  have  a  pleasure  in  dedicating  it.  The  outline  of 
a  young  specimen  is  very  similar  to  a  variety  of  V. 
dilatatus,  but  the  thinness  of  the  shell,  colour  of  in- 
terior, and  particularly  the  form  of  the  teeth,  will 
readily  distinguish  it.  The  old  shell  might  perhaps 
be  mistaken  for  a  variety  of  the  U.  rectus,  but  the 
young  has  very  little  resemblance  to  that  of  the  latter. 
U.  dilatatus  is  found  in  company  with  this  species, 
retaining  all  the  peculiarity  of  habit  which  it  pos- 
sesses in  the  Ohio  and  other  tributaries  of  the  Missis- 
sippi, which  confirms  our  opinion  that  the  shell  we 
described  above  is  new  and  distinct. 


UNIO  LAPILLUS.  . 

Plate  XXIX.— Fig.  2. 

DESCRIPTION. 

Shell  suboval,  thick,  yellowish,  with  very  numerous 
dark  green  undulated  rays;  anterior  margin  not  very 
short,  rounded;  beaks  but  little  elevated,  simple;  liga- 
ment margin  declining  gradually  in  an  arcuate  line; 
posterior  extremity  rounded;  umbonial  slope  unde- 
fined; basal  margin  straight  or  slightly  contracted  in 
the  middle;  within  pearly  white;  cardinal  teeth  direct, 
thick;  lateral  teeth  thick,  oblique;  cicatrices  very  deep 
and  rounded;  cavity  of  the  beaks  almost  obliterated. 

SYNONYMES. 

U.  lapillus,  Say.     Trans.  Journ.  of  Med.  vol.  iv.  p.  528,  Amer. 
Conch,  pi.  41. 


55 

U.  fabalis,  Lea.    Trans.  Amer.  Philos.  Soc.  vol.  iv.  p.  96,  pi.  x. 

fig.  16. 
Cab.  A.  N.  S.  No.  2404. 

OBSERVATIONS. 

Mr.  Say  observes  that  "the  robust  teeth  and  the 
thickness  of  the  whole  shell  have  induced  many,  and 
myself  amongst  the  number,  to  consider  this  shell  as 
the  young  of  gibbosus,  Barnes,  \dilatatus,  Raf.]  but  a 
very  slight  examination  serves  to  show  that  it  is  very 
distinct.  The  young  of  that  species  is  always  much 
more  elongated  transversely,  not  so  thick,  with  the 
beaks  much  undulated,"  &c. 

It  is  usually  smaller  than  the  specimen  represented, 
and,  except  the  acutissimas,  is  the  least  of  North 
American  Uniones  yet  described.  Dr.  Sager  found 
it  in  Detroit  river,  Michigan,  and  it  is  not  uncommon 
in  the  Ohio  and  its  tributaries.  The  figure  repre- 
sents a  fine  specimen,  of  more  than  ordinary  size, 
which  we  owe  to  the  politeness  of  Professor  J.  Green. 


UNIO  FRAGILIS. 

Plate  XXX. 

DESCRIPTION. 

Shell  ovate,  thin,  fragile,  somewhat  inflated  over 
the  umbonial  slope;  disks  flattened  towards  the  base; 
hinge  margin  elevated  into  a  large  wing,  connate; 
within  bluish  and  highly  iridescent;  cardinal  teeth 
very  oblique,  compressed,  disposed  to  be  single  in 
each  valve;  lateral  teeth  arcuate. 


56 

SYNONYMES. 

U.  fragilis,  Raf.  Ann.  gen.  des  Sc.  Phys.  vol.  v.  p.  29.  Poul- 
son's  trans,  p.  22.     Say,  Amer.  Conch.  No.  6. 

U.  gracilis,  Barnes.     Silliman's  Journ.  vol.  vi.  p.  174. 

U.  fragilis,  Swains. 

Symphyxota  gracilis,  Lea.  Trans.  Amer.  Philos.  Soc.  new  se- 
ries, vol.  iii.  p.  66. 

Cab.  A.  N.  S.  No.  1657. 

OBSERVATIONS. 

Allied  to  U.  alatus,  but  is  longer  in  proportion, 
thinner,  and  lighter  coloured  in  the  interior  and  epi- 
dermis. In  some  localities  the  wing  is  small,  but  in 
others  generally  elevated. 

Found  by  Mr.  Schoolcraft  in  Fox  river;  it  inhabits 
the  Detroit  river,  Michigan,  lakes,  and  the  western 
rivers  generally,  and  I  found  it  common  in  the  Ala- 
bama at  Claiborne. 


UNIO  ALATUS. 

Plate  XXXI. 

DESCRIPTION. 


Shell  triangular,  ovate,  moderately  thick;  disks 
flattened  anteriorly,  and  inflated  over  the  umbonial 
slope;  anterior  side  narrow,  margin  obliquely  recti- 
linear above;  posterior  side  profoundly  dilated,  and 
rising  into  an  elevated  connate  wing;  umbo  oblique, 
inclined,  not  prominent;  posterior  lunule  with  two 
subangulated  lines;  umbonial  slope  regularly  rounded; 
wing  emarginate  inferiorly;  posterior  end  biangulated; 


57 

epidermis  dark  green-olive,  wrinkled;  wrinkles  lamel- 
liform  posteriorly;  within  reddish-purple,  iridescent; 
cardinal  teeth  direct,  double  in  each  valve;  lateral 
teeth  arcuate. 

SYNONYMES. 

U.  alatus,  Say.     Nich.  Enc. ,  Am.  ed.,  art.  Conch. 

U.  (metaptera)  megaptera,  Raf.    Ann.  gen.  des  Sc.  Phys.,  vol. 

v.  p.  299. 
Symphynota  alata,  Lea.    Trans.  Amer.  Phil.  Soc,  (new  series,) 

vol.  iii.  p.  448. 
Cab.  A.  N.  S.  No.  20409. 

OBSERVATIONS. 

This  well  known  species  approaches  a  variety  of 
U.  purpuratus,  Lam.,  but  is  less  inflated  and  has  a 
more  elevated  wing.  From  the  fragilis  it  can  be 
distinguished  by  its  larger  size,  dark  epidermis,  purple 
nacre,  thicker  cardinal  teeth,  &c. 

Inhabits  Fox  and  Ouisconsin  rivers,  North- West 
Territory,  Mr.  Barnes;  Detroit  river,  Michigan,  Dr. 
Sager;  western  streams  generally,  and  the  great  lakes. 
It  is  extremely  rare  in  South  Alabama. 


UNIO  INFLATUS. 

Plate  XXXII. 

DESCRIPTION. 


Shell  triangular,  ovate,  thin;  contracted  obliquely 
from  beak  to  base;  inflated  over  the  umbonial  slope; 
valves  elevated  into  a  small  wing  anteriorly  and  into 

H 


58 

a  broad  high  wing  posteriorly,  and  connate  in  both; 
posterior  margin  of  the  wing  arcuate,  and  slightly 
emarginate  or  angulated  at  base;  beaks  slightly  pro- 
minent; cardinal  teeth  single  in  both  valves,  and 
lamelliform;  lateral  teeth  arcuate,  prominent  towards 
the  extremity;  nacre  purple. 

SYNONYMES. 

Symphynota  inflata,  Lea.    Trans,  Amer.  Phil.  Soc. ,  new  series, 

vol.  iv.  p.  99,  pi.  xiv.  fig.  28. 
U.  Alabamensis,  Nob.    New  Fresh  Water  Shells,  p.  67. 
Cab.  Ji.  N.  S.  No.  20405. 

OBSERVATIONS. 

Differs  from  U.  (Symphynota)  lavissimus  in  the 
inflated  umbonial  slope  and  more  elevated  wing.  It 
was  discovered  near  Claiborne,  Alabama,  by  Judge 
Tait,  and  sent  to  Mr.  Lea.  I  have  since  found  it 
very  abundantly  a  few  miles  south  of  Claiborne,  but 
it  is  rare  in  the  upper  part  of  the  Alabama  and  in  the 
Black  Warrior  rivers,  and  has  not  hitherto  been  found 
elsewhere. 


UNIO  LEPTODON. 

Plate  XXXIII. 
DESCRIPTION. 


Shell  narrow-elliptical,  very  thin  and  fragile,  com- 
pressed anteriorly,  and  slightly  inflated  over  the  um- 
bonial slope;  beaks  very  small,  approximate;  posterior 


59 

side  produced,  pointed;  hinge  margin  elevated;  pos- 
terior margin  very  oblique,  extremity  acutely  angular, 
and  much  above  the  line  of  the  base;  basal  margin 
regularly  arcuate;  epidermis  olive-yellow,  with  very 
oblique  narrow  rays;  within  bluish,  tinged  with  violet 
above,  highly  iridescent;  cardinal  teeth  obtuse,  smooth, 
nearly  obsolete;  lateral  teeth  single  in  each  valve. 

SYNONYMES. 

U.  leptodox,  Raf.     Ann.  gen.  des  Sc.  Phys.,  vol.   v.   p.  295. 

Poulson's  trans.,  p.  21.     Say,  Amer.  Conch.  No.  6.     Ferr. 

Mag.  de  Zool. 
U.  planus,  Barnes.     Silliman's  Journal,  vol.  vi.  p.  272. 
Anodonta  purpurascens,  Swainson. 
Symphynota  tenuissima,  Lea.     Trans.  Amer.  Philos.  Soc,  (new 

series,)  vol.  iii.  p.  453,  pi.  xi.  fig.  21. 
Cab.  A.  N.  S.  No.  20406. 

OBSERVATIONS. 

This  shell  has  an  exterior  much  resembling  that  of 
an  Anodonta,  but  the  teeth  are  generally  sufficiently 
developed  to  constitute  it  a  true  Unio.  It  is  allied 
to  V.fragilis,  but  differs  widely  in  the  teeth,  in  being 
pointed  posteriorly,  and  in  not  being  alated.  It  is 
connate  when  perfect. 

Inhabits  the  Ouisconsin,  Mr.  Barnes.  I  found  a 
single  specimen  in  Alabama.  The  specimen  figured 
is  from  the  Scioto  river,  and  was  presented  by  Dr. 
William  Blanding. 


60 


UNIO  ELLIPSIFORMIS. 

Plate  XXXIV.— Fig.  1. 

DESCRIPTION. 

Shell  elliptical,  slightly  ventricose,  produced  pos- 
teriorly, moderately  thick;  disks  slightly  contracted 
anteriorly;  umbonial  slope  rounded;  beaks  slightly 
prominent,  approximate,  simple;  basal  margin  dilated 
posteriorly  to  the  middle;  within  bluish;  cardinal  teeth 
thick,  direct. 

OBSERVATIONS. 

This  species  I  have  seen  only  in  the  cabinet  of  Mr. 
John  Phillips,  who  received  it  from  Michigan.  It  is 
very  similar  in  outline  to  U.  lienosas,  but  the  short, 
thick,  direct  teeth,  simple  beaks,  and  bluish  nacre, 
form  a  very  distinctive  character. 


UNIO  LIENOSUS. 

Plate  XXXIV.— Fig.  2. 

DESCRIPTION. 

Shell  elliptical,  inflated,  slightly  furrowed  or  con- 
tracted from  beak  to  base;  substance  of  the  shell 
thickened  towards  the  base;  posterior  dorsal  and 
posterior  basal  margin  rounded,  extremity  subangu- 
lated;  beaks  pointed,  approximate,  slightly  prominent, 


61 

with  interrupted  undulations;  concentric  lines  promi- 
nent; epidermis  dark  olive,  obscurely  rayed,  wrinkled 
on  the  margins;  cardinal  teeth  double  in  both  valves, 
slightly  compressed,  oblique,  striated;  nacre  varying 
from  bluish  white  to  deep  salmon  or  purple;  cavity 
most  capacious  under  the  umbonial  slope. 

SYNONYMES. 

U.  lienosus,  Nob.     Silliman's  Journal,  vol.  xxv.  p.  339,  pi.  1, 

fig.  4. 
U.  Nashvilliantjs,  Lea.     Trans.  Amer.  Phil.  Soc,  (new  series,) 

vol.  v.  p.  100,  pi.  xiv.  fig.  43. 
Cub.  A.  N.  S.  No.  20407. 

OBSERVATIONS. 

This  shell  is  remarkable  for  inhabiting  exclusively 
the  small  streams,  and  is  common  in  Greene  county, 
Alabama.  It  is  a  variable  species,  sometimes  not 
easily  recognised,  and  the  sexual  distinctions  are  as 
obvious  as  in  U.  siliquoideus.  The  colour  of  the  in- 
terior is  remarkably  inconstant,  but  a  purple  ap- 
proaching to  salmon  is  the  most  prevailing  tint,  and 
the  margin  is  bluish-white.  The  affinities  are  U. 
parvus,  Barnes,  and  U.  glans,  Lea,  but  it  is  much 
larger  than  either,  has  very  different  beaks,  and  does 
not  inhabit  the  same  waters  with  those  species. 


62 


UNIO  STAPES. 

Plate  XXXV.— Fig.  1. 

DESCRIPTION. 

Shell  subtriangular,  compressed,  thick;  anterior  side 
with  numerous  approximate,  angulated,  slightly  ele- 
vated tubercles;  disks  with  a  distinct  furrow  from 
beaks  to  base;  umbonial  slope  swelling;  posterior 
slope  greatly  contracted,  tuberculated,  angulated  sub- 
medially,  and  forming  a  right  angle  with  the  umbonial 
slope;  posterior  margin  direct,  forming  a  regular  curve 
with  the  ligament  margin;  emarginate  inferiorly;  base 
slightly  emarginate;  within  white;  cardinal  teeth  thick, 
direct;  lateral  teeth  short,  very  oblique. 

SYNONYME. 

U.  stapes,  Lea.     Trans.  Amer.  Phil.  Soc,  (new  series,)  vol.  iv. 

p.  77,  pi.  vii.  fig.  8. 
Cab.  A.  N.  S.  No.  20408. 

OBSERVATIONS. 

A  rare  species,  remarkable  for  the  small  area  be- 
hind the  umbonial  slope,  which  gives  it  somewhat  the 
form  of  U.  trwicatus,  Raf.  It  approaches  nearest  to 
the  metancvra,  but  is  very  distinct.  The  shell  is  not 
in  the  least  oblique,  and  the  beaks  are  central,  flat- 
tened and  prominent.  I  found  it  only  in  the  Alabama 
river,  near  Claiborne,  where  it  was  first  obtained  by 
Judge  Tait  and  forwarded  to  Mr.  Lea. 


63 


UNIO  INTERMEDIUM 

Plate  XXXV.— Fig.  2. 

DESCRIPTION. 

Shell  suboval,  compressed;  disks  flattened  or  slight- 
ly furrowed  from  beaks  to  base,  covered,  except  on 
the  posterior  side,  with  small  slightly  elevated  tuber- 
cles, which  are  rib-shaped  on  the  posterior  slope; 
umbonial  slope  not  prominent,  and  rounded  or  sub- 
angulated;  posterior  slope  obtusely  angulated;  beaks 
oblique,  not  prominent;  ligament  margin  long,  arcu- 
ate; posterior  margin  direct,  emarginate;  within  white; 
cardinal  teeth  direct. 

OBSERVATIONS. 

Three  specimens  of  this  species  were  obtained  by 
Dr.  S.  Blanding,  of  Columbia,  S.  C,  from  Nolachucky 
river,  Tennessee,  and  were  kindly  submitted  to  my 
inspection.  They  differ  from  the  preceding  in  being 
somewhat  oblique,  in  having  less  prominent  beaks,  a 
wider  posterior  slope,  but  particularly  in  being  desti- 
tute of  tubercles  anteriorly.  From  the  metanevra  it 
is  easily  distinguished  by  the  want  of  a  swelled  um- 
bonial slope.  It  is  so  evident  a  link  between  these 
two  species,  that  I  have  given  it  the  name  of  inter- 
medins, suggested  by  my  friend  Mr.  John  Phillips. 
In  a  young  specimen  which  I  have  figured,  the  epi- 
dermis is  covered  with  small  crowded  angular  green 
spots,  but  in  the  old  shell  they  disappear.  The  latter 
becomes  distinctly  angulated  or  furrowed  on  the  pos- 


64 


terior  slope,  and  profoundly  emarginate  posteriorly, 
as  represented  in  the  outline,  fig.  3. 


UNIO  OCCIDENTALS. 

Plate  XXXVI.— Fig.  1. 

DESCRIPTION. 

Shell  elliptical,  convex,  anterior  margin  very  regu- 
larly rounded;  anterior  dorsal  margin  elevated;  basal 
margin  straight  and  parallel  with  the  ligament  mar- 
gin; posterior  margin  oblique,  extremity  rounded; 
umbonial  slope  undefined;  beaks  slightly  prominent, 
with  undulated  grooves;  summit  rounded;  epidermis 
yellowish,  with  narrow  green  rays,  which  are  obso- 
lete or  wanting  on  the  anterior  side;  within  bluish; 
cardinal  teeth  direct,  prominent,  acute;  lateral  teeth 
lamelliform. 

OBSERVATIONS. 

This  shell  has  an  outline  similar  to  that  of  U.  com- 
planatus.  It  differs  from  that  species  in  its  yellow 
epidermis,  the  peculiarity  of  its  rays,  more  elevated 
anterior  margin,  lamelliform  lateral  teeth,  &c. 

Inhabits  Currant  river,  Arkansas,  whence  it  was 
brought  by  Mr.  Featherstonhaugh,  to  whose  kindness 
I  owe  the  use  of  this  and  several  rare  and  beautiful 
species. 


65 


UNIO  COLLINUS. 

Plate  XXXVI.— Fig.  2. 

DESCRIPTION. 

Shell  elliptical,  rather  thin,  with  coarse  concentric 
lines;  umbonial  slope  rounded;  posterior  side  slightly 
produced,  and  rapidly  narrowed  to  the  extremity, 
which  is  rounded;  basal  margin  straight  near  the 
middle;  beaks  small,  slightly  prominent,  approximate, 
undulated;  umbones  with  two  or  three  small  tubercles 
posterior  to  the  middle;  epidermis  yellowish-brown, 
obscurely  rayed;  within  white  or  pale  rose  colour; 
cardinal  teeth  oblique,  robust. 

Cab.  A.  N.  S.  No.  20408. 

OBSERVATIONS. 

This  species  may  readily  be  known  by  the  small 
tubercles  on  the  umbones.  The  female,  when  young, 
closely  resembles  U.  heterodon  in  outline,  but  the  usual 
formation  of  the  lateral  teeth  and  the  tubercles  emi- 
nently distinguish  it.  Inhabits  North  river,  a  branch 
of  James  river,  Virginia,  where  it  was  found  by  Mr. 
Constant  Newkirk,  of  Washington  College,  from 
whom  I  received  three  specimens. 


66 


UNIO  SOWERBIANUS. 

Plate  XXXVII.— Fig.  1. 

DESCRIPTION. 

Shell  ovate,  convex,  with  concentric  furrows;  disks 
slightly  gibbose  in  the  middle;  posterior  side  with  a 
furrow  from  beak  to  base;  a  slight  groove  on  the  pos- 
terior submargin;  raised  radiating  lines  extend  from 
the  angle  of  the  larger  furrow  to  the  posterior  extre- 
mity, which  is  direct  and  slightly  retuse;  basal  margin 
retuse  posteriorly;  epidermis  glabrous,  with  faint  fili- 
form brown  rays;  within  purple  or  rose  colour;  car- 
dinal teeth  very  large  and  prominent,  double  in  each 
valve. 

SYNONYME. 

U.  sowerbiaxus,  Lea.    Trans.  Amer.  Phil.  Soc,  new  series,  vol. 
v.  p.  68,  pi.  x.  fig.  28. 

OBSERVATIONS. 

The  fine  specimen  of  this  beautiful  and  very  distinct 
species  which  I  have  figured,  was  kindly  loaned  for 
the  purpose  by  Mr.  Featherstonhaugh,  who  procured 
it  from  Cumberland  river,  Tennessee.  I  found  one 
in  the  summer  of  1833  on  the  bank  of  Elk  river, 
Alabama,  and  judging  from  Mr.  Lea's  figure  of  the 
pileus,  I  supposed  it  to  be  that  species.*  The  speci- 
men is  in  the  cabinet  of  Mr.  Poulson. 

The  Sowerbianus  is  remarkable  for  its  highly  po- 
lished epidermis  and  raised  lines  on  the  posterior  side. 

*  New  Fresh  Water  Shells,  p.  69,  note. 


67 


UNIO  POLITUS. 

Plate  XXXVII.— Fig.  2. 

DESCRIPTION. 

Shell  suborbicular,  convex,  with  slight  concentric 
furrows;  anterior  margin  obtusely  rounded;  posterior 
margin  nearly  direct;  ligament  margin  rectilinear, 
slightly  declining;  umbonial  slope  rounded;  disks  flat- 
tened or  very  indistinctly  furrowed  posteriorly;  basal 
margin  rounded,  or  slightly  gibbous  in  the  middle; 
epidermis  glossy,  with  fine  concentric  wrinkles;  umbo 
prominent,  smooth  and  polished,  with  dark  green 
interrupted  rays;  within  white;  cardinal  teeth  thick, 
very  direct. 

SYNONYMES. 

U.  politus,  Say.     Amer.  Conch.,  No.  6. 

U.  subrotundus,  Lea.    Trans.  Amer.  Phil.  Soc,  new  series,  vol. 

iv.  p.  117,  pi.  xviii.  fig.  45. 
Cab.  A.  N.  S.  No.  20409. 

OBSERVATIONS. 

Related  to  U.  Kirtlandicus,  Lea,  from  which  it  dif- 
fers in  being  proportionally  more  elevated  and  much 
less  compressed.  It  is  also  a  smaller  species.  The 
name  of  subrotundus  has  necessarily  been  abandoned, 
as  it  is  preoccupied  for  a  different  species. 


68 


UNIO  NEXUS. 

Plate  XXXVIIL— Fig.  1. 

DESCRIPTION. 

Shell  triangular,  sub-rhomboidal,  much  inflated, 
thick;  umbo  prominent;  posterior  slope  much  de- 
pressed, with  a  broad,  shallow  groove,  which  extends 
from  the  beak  to  the  posterior  margin;  posterior 
margin  forming  nearly  a  right  angle  with  the  base, 
obtusely  emarginate  in  the  middle  by  the  termination 
of  the  groove;  umbonial  slope  carinated,  in  conse- 
quence of  the  depression  of  the  posterior  side;  lunule 
very  short;  epidermis  yellowish-brown,  obsoletely  ra- 
diated; within  white;  cardinal  teeth  direct;  lateral 
teeth  short,  with  but  little  obliquity. 

SYNONYMES. 

U.  nexus,  Say.     Trans.  Journ.,  vol.  iv.  p.  527,  1831.     Amer. 

Conch.,  pi.  li. 
U.  arcjEfokmis,  Lea.     Trans.  Amer.  Phil.  Soc,  new  series,  vol. 

iv.  p.  116,  pi.  xvii.  fig.  44. 
Cab.  rf.N.  S.No.  20410. 

OBSERVATIONS. 

Mr.  Say  remarks  that  this  species  is  "related  to 
triqueter,  Raf.,  but  differs  in  the  greater  prominence 
of  the  superior  portion  of  the  anterior  [posterior] 
margin."  There  is  also  a  great  difference  in  the 
teeth  and  in  the  markings  of  the  epidermis,  which  in 
the  nexus  are  filiform  rays,  but  in  the  triqueter  gene- 
rally sagittate  spots.    Not  uncommon  in  the  Cumber- 


69 

land  river,  and  it  seems  chiefly  confined  to  the  waters 
of  Tennessee — I  saw  none  in  Alabama.  The  figure 
is  from  a  specimen  in  the  cabinet  of  Mr.  Feather- 
stonhaugh. 


UNIO  GREENIL 

Plate  XXXVIII.— Fig.  2. 
DESCRIPTION. 

Shell  sub-triangular;  disks  slightly  flattened;  ante- 
rior side  not  very  short,  margin  rounded,  not  very 
obtuse;  umbo  flattened,  not  elevated;  beaks  eroded; 
umbonial  slope  straight,  subangulated;  ligament  short, 
ligament  margin  forming  with  the  posterior  margin  a 
nearly  regular  arcuate  line;  extremity  obtusely  round- 
ed or  subtruncated;  basal  margin  slightly  arcuate; 
epidermis  wrinkled  on  the  margins,  with  narrow 
green  rays  on  the  posterior  slope  and  interrupted 
rays  on  the  umbo;  within  white;  cardinal  teeth  slightly 
oblique;  lateral  teeth  oblique  and  very  slightly  curved. 

SYNONYME. 

IT.  greenii,  Nob.     New  Fresh  Water  Shells,  p.  32,  pi.  iv.  fig.  1. 
Cub.  A.  N.  S.  No.  20413. 

OBSERVATIONS. 

Dedicated  to  my  friend  Jacob  Green,  M.  D.,  Pro- 
fessor of  Chemistry  in  Jefferson  College,  a  gentleman 
well  known  as  a  contributor  to  Conchology.  Inhabits 
the  head  waters  of  Black  Warrior  river,  Alabama; 
not  uncommon. 


70 


UNIO  SHEPARDIANUS. 

Plate  XXXIX. 

DESCRIPTION. 

Shell  profoundly  elongated,  sinuous,  compressed, 
tapering  to  the  posterior  extremity,  which  is  trun- 
cated; valves  rather  thin,  with  concentric  lines,  pro- 
found over  the  umbonial  slope,  which  is  slightly  ele- 
vated; a  carinated  line  passes  between  the  umbonial 
slope  and  posterior  dorsal  margin;  beaks  very  small, 
hardly  raised  above  the  dorsal  line;  within  purple; 
lateral  teeth  long  and  rectilinear,  somewhat  dilated 
or  thickened  near  the  anterior  termination. 

SYNONYME. 

U.  shepardianus,  Lea.    Trans.  Amer.  Phil.  Soc,  new  series,  vol. 

v.  p.  95,  pi.  xiii.  fig.  38. 
Cab.  A.  N.  S.  No.  20411. 

OBSERVATIONS. 

This  is  perhaps  the  most  elongated,  proportionally, 
of  any  known  Unio,  except  the  Graymius,  and  differs 
chiefly  in  this  respect  from  U.  angustatus,  which  is 
the  species  most  nearly  related  to  it. 

Inhabits  Alatamaha  river,  near  Hopeton  and  Da- 
rien,  Georgia. 


71 


UNIO  COMPRESSUS. 

Plate  XL. — Fig.  1. 
DESCRIPTION. 

Shell  oblong  or  elliptical;  disks  flattened;  anterior 
margin  regularly  rounded;  umbonial  slope  slightly 
elevated,  rounded;  beaks  undulated,  not  prominent, 
distant  from  the  anterior  extremity;  ligament  margin 
elevated,  connate;  posterior  margin  oblique,  recti- 
linear, extremity  truncated  and  slightly  projecting 
beyond  the  line  of  the  base;  epidermis  ochraceous, 
with  numerous  unequal  green  rays,  some  of  which 
are  very  broad;  within  white,  tinged  with  pale  salmon 
under  the  beaks;  cardinal  tooth  scarcely  double  in 
the  right  valve,  very  oblique,  elongated,  rather  thick; 
in  the  left  valve  widely  trifid,  compressed,  posterior 
lobe  rather  behind  the  apex. 

SYNONYMES. 

U.  compressus,  Deshayes. 

Symphynota  compressa,  Lea.     Trans.  Amer.  Phil.   Soc,  (new 

series,)  vol.  iii.  p.  450,  pi.  xii.  fig.  22. 
Cab.  A.  N.  S.  No.  1098. 

OBSERVATIONS. 

This  species  can  at  once  be  distinguished  from  all 
others  by  the  peculiarity  of  its  hinge.  It  inhabits 
the  Ohio,  Scioto,  and  Wabash  rivers;  also  Oak  Orch- 
ard creek,  in  the  State  of  New  York,  and  Norman's 
Kill,  near  Albany.  The  figure  is  from  a  specimen 
which  I  found  in  a  mill  pond  at  the  village  of  Adams, 


72 


Jefferson  county,  New  York,  where  the  species  is 
extremely  abundant. 


UNIO  CAPS^FORMIS. 

Plate  XL. — Fig.  2. 
DESCRIPTION. 

Shell  sub-oval,  slightly  ventricose,  moderately 
thick;  posterior  side  flattened  or  very  slightly  grooved; 
umbonial  slope  obtusely  angulated;  basal  margin 
rounded  medially,  straight  or  slightly  emarginate 
posteriorly;  posterior  extremity  direct,  truncated, 
narrowed,  slightly  produced;  summits  obtusely  round- 
ed, not  prominent;  epidermis  yellowish,  with  nume- 
rous narrow  unequal  green  rays;  within  white;  cardi- 
nal teeth  very  erect  and  prominent. 

SYNONYME. 

U.  caps.eformis,  Lea.     Trans.  Amer.  Philos.  Soc,  new  series, 

vol.  iv.  p.  143,  pi.  ii.  fig.  4. 
Cab.  A.  N.  S.  No.  20414. 

OBSERVATIONS. 

Inhabits  Cumberland  river  near  Nashville,  Tennes- 
see. I  have  found  it  in  the  Tennessee  river  at  Flo- 
rence, Alabama.  It  bears  a  slight  resemblance  to 
the  young  of  U.flexuosas,  and  is  a  very  distinct  spe- 
cies. The  female  is  represented  in  figure  3.  Be- 
tween the  sexes  the  difference  in  outline  is  greater 
than  in  any  species  with  which  we  are  acquainted, 
except  U.  gibbosus,  Raf. 


73 

The  two  fine  specimens  figured  belong  to  the 
splendid  collection  of  Mr.  Poulson.  They  were  sent 
from  Nashville,  Tennessee. 


UNIO  SUBPLANUS. 

Plate  XLL— Fig.  1. 
DESCRIPTION. 

Shell  sub-oval;  disks  flattened;  anterior  margin 
regularly  rounded,  obliquely  descending;  umbonial 
slope  rounded;  posterior  slope  dilated;  beaks  not  pro- 
minent, distant  from  the  anterior  extremity;  ligament 
margin  elevated,  slightly  oblique;  posterior  extremity 
truncated;  epidermis  yellowish-brown,  with  numerous 
fine  concentric  wrinkled  lines;  within  pale  rose  colour; 
cardinal  teeth  oblique;  lateral  teeth  rectilinear. 

Cab.  A.  N.  S.  No.  20412. 

OBSERVATIONS. 

I  have  recently  received  several  specimens  of  this 
shell  from  Lexington,  Rockbridge  county,  Virginia, 
where  they  were  found  by  Mr.  Newkirk  in  a  branch 
of  the  James  river.  Approaches  U.  Masoni,  but  is 
more  compressed  and  elongated,  and  cannot  be  con- 
founded with  it. 


K 


UNIO  FLAVUS. 

Plate  XLI. — Fig.  2. 

DESCRIPTION. 

Shell  sub-triangular,  moderately  thick;  disks  flat- 
tened on  the  posterior  side;  anterior  margin  obtusely 
rounded;  ligament  margin  oblique,  rectilinear;  poste- 
rior margin  wide,  straight,  nearly  direct;  extremity 
obtuse;  basal  margin  straight  from  the  posterior  ex- 
tremity to  beyond  the  middle;  umbonial  slope  cari- 
nated;  umbo  rather  prominent;  beaks  flattened,  with 
a  few  obtuse  oblique  undulations;  within  salmon 
colour;  cardinal  and  lateral  teeth  large  and  very  pro- 
minent. 

SYNONYMES. 

U.  flava,  Ef.     Ann.  gen.   des  Sc,    vol.  v.  p.  59.     Poulsoirs 

trans.,  p.  38. 
U.  rueiginosus,  Lea.     Trans.  Amer.  Phil.  Soc.,  new  series,  vol. 

iii.  p.  41,  pi.  viii.  fig.  10. 
Cab.  A.N.  S.Xo.  1126. 

OBSERVATIONS. 

This  shell  is  so  distinctly  described  and  even  figured 
by  Rafinesque,  that  no  honest  inquirer  can  refuse 
him  credit  for  the  species.  He  remarks  that  he  found 
"it  only  in  the  small  rivers  falling  into  the  Kentucky, 
Salt  or  Green  rivers."  This  peculiarity  of  habitat 
is  remarkable,  and  I  Avas  unable  to  find  a  specimen 
in  either  the  Alabama,  Tombeckbe,  or  Black  Warrior 
rivers,  although  several  were  found  in  a  small  mill 
stream  in  Greene  county,  Alabama.     Rafinesque  re- 


75 

marks  that  the  "young  shells  are  almost  yellow,  and 
the  animal  of  a  deep  or  orange-yellow  colour,"  which 
accords  with  my  own  observation.  I  do  not,  how- 
ever, consider  the  colour  of  the  animal  any  safe  guide 
in  specific  distinction,  as  I  have  found  the  same  spe- 
cies, particularly  V.  decisus,  to  contain  in  some  spe- 
cimens an  orange  coloured,  and  in  others  a  perfectly 
white  animal. 


UNIO  CAPAX. 

Plate  XLII. 

DESCRIPTION. 

Shell  very  globose;  valves  rather  thin,  translucent, 
connate;  umboncs  tumid,  summit  obtusely  rounded, 
prominent,  distant  from  the  anterior  margin;  epider- 
mis straw  colour,  polished,  with  two  faint  green  rays 
on  the  posterior  slope;  within  white  and  iridescent; 
cardinal  teeth  lamellar,  prominent,  double  in  the  right 
valve,  crenate  and  single  in  the  left;  lateral  teeth 
arcuate. 

SYNONYMES. 

U.  capax,  Green.     Cab.  of  Nat.  Hist,  vol.  ii.  p.  290.    1832. 
Symphynota  globosa,  Lea.    Trans.  Amer.Phil.  Soc,  new  series, 

vol.  iv.  p.  153,  pi.  iv.  fig.  12.   1834. 
Cab.  A.  N.  S.  No.  1227. 

OBSERVATIONS. 

The  most  ventricose  of  all  the  Unios  known,  and, 
when  young,  one  of  the  most  delicate  and  beautiful. 


76 

It  most  nearly  resembles  U.  cariUum,  Raf.,  but  the 
tumid  umbones  will  always  prove  a  destructive  cha- 
racter. Dr.  Green  was  the  first  to  recognise  this  as 
an  undescribed  species,  and  his  name,  having  priority, 
must  necessarily  be  adopted.  He  observes,  "I  now 
describe  a  fine  large  shell,  which  seems  to  have 
escaped  the  notice  of  our  conchologists.  The  first 
specimens  of  this  shell  which  I  observed  were  from 
the  Falls  of  St.  Anthony.  I  afterwards  received  it 
from  the  Bayou  Teche,  but  I  never  discovered  or 
ascertained  that  it  exists  in  the  Ohio."  Mr.  Lea,  on 
the  authority  of  Col.  Long,  informs  us  that  it  inhabits 
the  Ohio,  150  miles  below  Louisville,  Ky. 


UNIO  RUDIS. 

Plate  XLIII.— Fig.  1. 

DESCRIPTION. 

Shell  ovate-acute,  thick  anteriorly;  diameter  great- 
est at  the  umbones;  beaks  eroded;  posterior  side 
cuneiform;  ligament  and  posterior  margins  arcuate, 
extremity  subangulated;  epidermis  brown,  wrinkled 
inferiorly;  within  white;  cardinal  teeth  small,  direct; 
lateral  teeth  slightly  arcuate. 

SYNONYME. 

TT.  ravenelianus,  Lea.    Trans.  Amer.  Phil.  Soc.,  new  series,  vol. 

iv.  p.  144,  pi.  iii.  fig.  5. 
Cab.  .tf.  N.  S.  No.  20415. 

OBSERVATIONS. 

Inhabits  French  Broad  river,  North  Carolina,  Dr. 


77 

Ravenel.     I  found  it  in  the  upper  part  of  the  Black 
Warrior  river,  Alabama,  where  it  is  rare. 

Resembles  U.  perovatus  in  outline,  but  the  shell  is 
far  greater  in  diameter  through  the  umbones,  and  the 
beaks  nearer  the  anterior  extremity.  The  most 
striking  character,  perhaps,  is  the  accurate  wedge- 
shaped  form  of  the  posterior  side.  Mr.  Lea  first 
published  this  species  under  the  name  of  Ravcnclianus, 
but  as  I  had  previously  published  a  different  species 
with  the  same  name,  I  am  compelled  to  substitute 
another. 


UNIO  OBLIQUUS. 

Plate  XLIIL— Fig.  2. 
DESCRIPTION. 

Shell  ovate-rotundate,  oblique;  disks  with  a  slight 
narrow  furrow  on  the  posterior  side;  umbonial  slope 
carinated;  posterior  slope  with  an  obtuse  carinated 
line;  ligament  and  posterior  margins  arcuate;  posterior 
extremity  obliquely  truncated;  beaks  very  prominent, 
curving  forward;  lunule  sagittate;  within  white;  car- 
dinal teeth  directed  obliquely  backwards;  lateral  teeth 
arcuate;  cardinal  plate  much  thickened  under  the 
cardinal  teeth,  contracting  the  cavity  of  the  umbo. 

SYNONYMES. 

U.  obliqua,  Lam.     An.  sans  Vert.,  vol.  vi.  p.  72.     Fcrus.  Mag. 

de  Zool. 
U.  ebenus,  Lea.     Trans.  Amer.  Phil.   Soc,  new  series,  vol.  iii. 

p.  94,  pi.  ix.  fig.  14. 
Cab.  A.  N.  S.  No.  1259. 


78 

OBSERVATIONS. 

Inhabits  the  Black  Warrior  and  Alabama  rivers, 
Avhere  I  found  it  in  abundance;  also  the  Ohio  and  its 
tributaries. 

The  ovate  form  of  this  species  and  its  obliquity 
will  distinguish  it  at  a  glance  from  undatus,  Barnes. 
The  young  is  remarkable  for  being  of  yellow  colour 
behind  the  umbonial  slope,  which  soon  disappears  in 
general  as  the  shell  increases  in  size. 

Mr.  Lea  appears  to  be  ignorant  of  the  true  distinc- 
tive character  of  this  species,  since  he  affirms  that  I 
have  published  it  under  the  name  of  mytiloides;  the 
latter  is  destitute  of  the  callosity  of  the  cardinal  plate 
which  characterizes  the  obligims,  has  a  very  different 
lunule,  and  is  dissimilar  in  outline  to  that  species. 
Those  who  are  conversant  with  the  two  shells  will 
not  confound  them. 

Mr.  Lea  considers  the  obliqua  of  Lamarck  to  be 
identical  with  undatus  of  Barnes,  but  Lamarck's  de- 
scription is  wholly  inapplicable  to  the  latter,  whilst 
it  agrees  with  the  cbenus  of  Lea,  with  which  it  is 
identical,  according  to  Ferussac. 


UNIO  APICULATUS. 

Plate  XLIV.— Fig.  1. 
DESCRIPTION. 


Shell  subquadrate,  compressed;  summits  not  very 
prominent;  hinge  margin  declining;  disks  with  a  dilat- 
ed  not   deeply   impressed    furrow;    umbonial   slope 


79 

arcuate,  carinated;  posterior  margin  dilated,  direct, 
produced,  and  rounded  or  subtruncated  at  base;  disks 
covered  with  small  subequal  tubercles,  arranged  more 
or  less  in  symmetrical  lines;  within  white. 

SYNONYMES. 

U.   apiculatus,  Say.    Disseminator,  1829.     American  Conch. 

pi.  52. 
U.  asper,  Lea.     Trans.  Amer.  Phil.  Soc,  new  series,  vol.  iii.  p. 

95,  pi.  ix.  fig.  15,  1832. 
Cab.  A.  N.  S.  No.  1877. 

OBSERVATIONS. 

Inhabits  the  Alabama  river,  near  Claiborne,  where 
I  found  specimens,  but  they  were  not  numerous  nor 
comparable  in  beauty  to  those  which  inhabit  Bayou 
Teche  in  Louisiana. 

Mr.  Say  thinks  this  may  prove  to  be  a  variety  of 
U.  guadrulus,  but  although  it  is  nearly  related  to  that 
species  we  believe  it  to  be  very  distinct.  Old  shells 
become  proportionally  more  elongated  and  produced 
at  the  posterior  extremity  of  the  basal  margin,  and 
the  tubercles  nearly  disappear  on  the  inferior  half  of 
the  disks.  The  figure  is  from  a  specimen  from  Bayou 
Teche. 


UNIO  PRASINUS. 

Plate  XLIV.— Fig.  2. 

DESCRIPTION. 


Shell  suborbicular,  compressed,  with  distant  con- 
centric  impressed  lines;    anterior   margin    obtusely 


80 

rounded;  posterior  margin  wide,  direct;  basal  margin 
straight,  parallel  with  the  ligament  margin;  summits 
rather  prominent;  disks  smooth,  with  a  few  very 
small  tubercles  on  the  posterior  side;  epidermis  olive- 
yellow,  very  broadly  rayed  with  green;  within  white. 

SYNONYMES. 

U.  prasinus,  Nob.  New  Fresh  Water  Shells,  p.  44.  May,  1834. 
U.  schoolcraftensis,  Lea.    Trans.  Amer.  Phil.  Soc.,  new  series, 

vol.  iv.  p.  149,  pi.  iii.  fig.  9.  Sept.  1834. 
Cab.  A.N.  S.No.  1128. 

OBSERVATIONS. 

Inhabits  the  Scioto  river,  Indiana. 

The  specimen  of  this  shell  in  the  cabinet  of  the 
Academy  of  Natural  Sciences  was  brought  by  Mr. 
Schoolcraft  from  Fox  river,  of  Green  Bay — others 
are  in  the  collection  of  Mr.  Hyde.  The  species  differs 
from  U.  bullatus,  Raf.,  in  being  of  a  suborbicular  out- 
line, more  compressed,  with  much  less  prominent 
beaks  and  fewer  tubercles.  Some  specimens  have  a 
few  rather  large  tubercles  near  the  base. 


UNIO  NODULATUS. 

Plate  XLV.— Fig.  1. 

DESCRIPTION. 

Shell  suborbicular,  slightly  ventricose,  moderately 
thick;  posterior  margin  direct,  retuse  in  the  middle; 
ligament  margin  straight,  elevated,  scarcely  declining; 
disks  with  two  series  of  distant  prominent  tubercles; 


81 

posterior  slope  dilated,  with  nodules  towards  the 
margin;  beaks  slightly  elevated,  granulate  at  tip; 
epidermis  olive-brown  and  rather  smooth;  within 
white;   cardinal  teeth  large   and  prominent;  lateral 

teeth  subrectilinear. 

i 

SYNONYMES. 

U.  nodulata,  Ruf.     Ann.  gen.  des  Sc.  Phys.,  vol.  v.  p.  41,  pi. 

lxxxi.  figs.  17,  18.    Poulson's  translation,  p.  42.    Say.  Ainer. 

Conch.,  No.  6.     Ferrus.  Mag.  de  Zool. 
U.  pustulatus,  Lea.     Trans.  Amer.  Phil.  Soc,  new  series,  vol. 

iv.  p.  79,  pi.  vii.  fig.  9. 
Cab.  A.  N.  S.,  No.  1755. 

OBSERVATIONS. 

Inhabits  the  Ohio  river  and  its  tributaries.  It  is 
related  to  U.  bullatus  and  U.  Mortoni.  From  the  for- 
mer it  differs  in  the  regularity  of  its  tubercles,  in  the 
dilatation  of  the  posterior  slope,  and  in  the  absence 
of  the  broad  green  ray  on  the  umbo.  From  the  latter 
it  may  be  distinguished  by  the  same  characters,  and, 
in  addition,  by  the  want  of  a  broad  depression  or 
furrow,  which  characterizes  U.  Mortoni.  Rafinesque's 
outlines  of  this  shell,  though  rude,  are  characteristic 
enough;  and  his  description,  though  short,  perfectly 
clear  and  applicable  to  this  species  only. 


82 


UNIO  BULLATUS. 

Plate  XLV.— Fig.  2. 
DESCRIPTION. 

Shell  elevated,  equilateral,  inflated,  irregularly  tu- 
berculated  on  the  middle  and  posterior  slope;  medial 
tubercles  generally  large;  substance  of  the  shell  thick; 
beaks  elevated  and  granulated  at  tip;  ligament  slope 
descending,  short;  posterior  margin  direct,  nearly 
straight;  epidermis  bright  brown,  a  single  broad  in- 
terrupted green  ray  passes  from  the  apex  to  the  middle 
of  the  disk;  within  white;  lateral  teeth  very  short, 
straight,  thick  and  oblique. 

SYNONYMES. 

U.  bullata,  Raf.    Ann.  gen.  des  Sc.  Phys.,  vol.  v.  p.  41.    Poul- 

son's  trans.,  p.  43. 
U.  verrucosus  albus,  Hild.    Silliman's  Journ.,  vol.  xiv.  p.  289. 
U.  pustulosus,  Lea.     Trans.  Amer.  Phil.  Soc,  new  series,  vol. 

iv.  p.  76,  pi.  vii.  fig.  7. 
Cab.  A.  N.  S.,  No.  1175. 

OBSERVATIONS. 

Inhabits  the  Ohio  and  its  tributaries,  Alabama  and 
Black  Warrior  rivers.  This  common  species  is 
easily  recognised,  and  will  be  found  to  differ  con- 
stantly from  U.  prasinus  by  its  more  elevated  and 
ventricose  form  and  more  numerous  tubercles.  It 
wants  the  furrow  of  the  Mortoni,  and  is  besides  dis- 
tinguished by  its  green  ray  and  larger  tubercles. 
The  white  colour  of  the  nacre  is  remarkably  constant, 


83 

as  I  have  never  found  it  to  vary  in  a  great  number 
of  specimens,  which  is  seldom  the  case  in  most  other 
species.  A  variety  is  remarkably  abundant  in  the 
Black  Warrior  river,  at  Erie,  Alabama. 

Mr.  Say  has  referred  this  species  to  U.  nodulosus, 
Wood,  but  the  figure  of  that  shell  in  Wood's  Con- 
chology  appears  to  me  to  represent  a  very  different 
species. 


UNIO  STEGARIUS. 

Plate  XLVL— Fig.  1. 
DESCRIPTION. 

Shell  elevated,  ovate;  valves  thick,  with  concentric 
furrows  and  ridges;  disk  with  a  narrow,  not  deeply 
impressed  furrow  from  beak  to  base;  umbo  and  beaks 
inclining  forward;  lunule  large,  ovate-acute,  very  dis- 
tinct; beaks  pointed  and  incurved;  umbonial  slope 
carinated  over  the  umbo;  epidermis  yellowish-brown, 
with  crowded,  fine,  green  dotted  rays,  and  broad 
rays,  composed  of  large  dots;  posterior  margin  direct; 
within  white;  cardinal  plate  greatly  dilated;  cardinal 
teeth  direct,  deeply  sulcated;  muscular  impressions 
small. 

SYNONYMES. 

U.  stegaria,  Raf.    Ann.  gen.  des  Sc.  Phys.,  vol.  v.   p.  46. 

Poulson's  translation,  p.  51.     Say,   Amer.   Conch.,  No.    6. 

Ferr.,  Mag.  de  Zool. 
U.  irroratus,  Lea.    Trans.  Amer.  Phil.  Soc,  new  series,  vol. 

iii.  p.  269,  pi.  v.  fig.  5. 
Cab.  A.  N.  S.,  No.  1122. 


84 

OBSERVATIONS. 

Inhabits  the  Ohio,  Scioto,  Wabash,  and  more 
rarely  the  rivers  of  Tennessee.  I  have  not  observed 
it  so  far  south  as  the  Tennessee  river,  in  Alabama. 
It  is  a  very  beautiful  species,  remarkable  for  its  very 
numerous  dotted  rays  and  its  regular  and  graceful 
outline,  which  approaches  that  of  U.  returns. 


UNIO  DROMAS. 

Plate  XLVL— Fig.  2. 

DESCRIPTION. 

Shell  obliquely  ovate;  disks  flattened  above,  and 
with  a  very  prominent  concentric  angular  ridge  in 
the  middle;  a  slight  furrow  from  beak  to  base  on  the 
posterior  side;  beaks  prominent,  summit  rather  wide, 
flattened;  lunule  angular;  epidermis  yellowish-brown, 
with  very  numerous  green  interrupted  capillary  rays, 
and  a  few  broad  rays;  within  white;  cavity  shallow. 

SYNONYME. 

U.  dromas,  Lea.     Trans.  Amer.  Phil.  Soc,  new  series,  vol.  v. 

p.  182,  pi.  x.  fig.  29. 
Cab.  Ji.N.  S.,No.  20416. 

OBSERVATIONS. 

Inhabits  Harpeth  and  Cumberland  rivers,  Tennes- 
see; Elk  river,  near  the  muscle  shoals,  Alabama.  I 
have  not  found  it  further  south. 

My  father,  many  years  since,  received  this  elegant 


85 

species  from  Harpeth  river,  Tennessee.  It  cannot 
be  confounded  with  U.  stegarius,  in  consequence  of 
its  remarkable  gibbose  disk.  The  rays  are  more 
strongly  marked  than  those  of  the  latter  species;  the 
disk  is  never  tuberculated,  whilst  the  stegarias  is 
sometimes  covered  with  tubercles,  as  Mr.  Lea  has 
stated  in  his  remarks  upon  the  dromas.  A  single 
valve  in  my  cabinet  measures  about  four  inches  from 
beak  to  base. 


UNIO  SUBTENTUS. 

Plate  XLVIL— Fig.  1. 
DESCRIPTION. 


Shell  oblong-suboval,  very  widely  and  slightly  con- 
tracted at  base;  summits  hardly  elevated,  decorti- 
cated, obtusely  rounded;  posterior  basal  angle  a  little 
prominent,  rounded;  posterior  dorsal  slope  with  nu- 
merous subramose,  slightly  arcuate,  oblique,  parallel 
costse;  epidermis  with  broad  interrupted  green  rays, 
sometimes  obsolete;  within  reddish-fulvous;  cavity  of 
the  umbo  not  deep;  cardinal  teeth  somewhat  direct, 
not  transverse;  lateral  teeth  slightly  arcuate. 

SYNONYME. 

U.  subtentus,   Say.     Jour.  Acad.  Nat.    8c,  vol.    v.   p.    130. 

Amer.  Conch.,  pi.  xv. 
Cab.  Ji.  N.  S.,  iVo.  20417. 

OBSERVATIONS. 

Mr.  Say  observes,  "  in  general  outline,  this  shell 


86 

has  some  resemblance  to  U.  purjmreus,  Nob.;  but  it 
is  distinguished  by  many  characters,  and  more  ob- 
viously by  the  character  of  the  anterior  costated 
margin.  It  is  a  native  of  South  Carolina,*  and  was 
sent  to  me  by  Professor  Vanuxem,  who  obtained  it 
from  the  North  Fork  of  the  Holston  river." 

Dr.  William  Blanding  presented  me  with  specimens 
from  Nollichucky  river,  Tennessee,  the  largest  of 
which  is  nearly  destitute  of  the  posterior  ribs.  I 
found  a  few  dead  shells  on  the  bank  of  Elk  river, 
near  the  muscle  shoals,  Alabama. 


UNIO  ACUTISSIMUS. 

Plate  XLVIL— Fig.  2. 
DESCRIPTION. 

Shell  narrow-elliptical;  posterior  side  produced, 
gradually  narrowed  to  a  point;  valves  thin;  posterior 
side  with  parallel  furrows  extending  from  the  umbo- 
nial  slope  to  base;  posterior  slope  with  slightly  arcuate 
ribs  and  furrows;  umbonial  slope  carinated;  beaks 
not  elevated  above  the  dorsal  line;  epidermis  yellow- 
ish, with  green  dotted  rays;  within  yellowish,  highly 
polished,  exhibiting  the  ribs  of  the  exterior. 

SYNONYME. 

U.  acutissimus,  Lea.    Trans.  Amer.  Phil.  Soc,  new  series,  vol. 

iv.  p.  89,  pi.  x.  fig.  18. 
Cab.  A.N.  S.,iVo.  20418. 

*  Mr.  Vanuxem  informs  me  that  he  found  it  in  Virginia. 


87 

OBSERVATIONS. 

Inhabits  the  Alabama  and  Black  Warrior  rivers: 
rare. 

This  is  one  of  the  smallest  species  of  Unio,  and 
resembles  the  young  of  the  conradius,  but  is  much 
more  elongated.  Mr.  Lea  observes  that  the  lateral 
teeth  are  single  in  each  valve;  but  the  specimens  be- 
fore me  have  the  usual  form  of  a  divided  tooth  in  the 
left  valve.  The  epidermis  is  marked  with  pale  green 
zig-zag  lines,  and  the  furrows  on  the  disk  are  some- 
times obsolete  or  wanting.  I  found  two  fine  indi- 
viduals at  the  village  of  Erie,  Greene  county,  Ala- 
bama, on  a  bar  in  the  Black  Warrior  river. 


UNIO  CONRADIUS. 

Plate  XLVIL— Fig.  3. 

DESCRIPTION. 

Shell  elliptical,  basal  margin  straight  or  slightly 
emarginate;  ligament  margin  slightly  declining;  valves 
rather  thin,  with  undulations  on  the  posterior  side, 
sometimes  obsolete;  posterior  slope  with  arcuate 
ribs;  beaks  very  slightly  prominent  and  undulated, 
decorticated;  epidermis  finely  wrinkled,  yellowish- 
brown,  with  numerous  green  rays;  within  inclining 
to  salmon  colour;  very  iridescent  and  furrowed  pos- 
teriorly. 

SYNONYME. 

U.  conradius,  Lea.   Trans.  Amer.  Phil.  Soc,  new  series,  vol.  v. 

p.  63,  pi.  ix.  fig.  23. 
Cab.  A.  N.  S.,  No.  20419. 


88 

OBSERVATIONS. 

Inhabits  Flint  river,  Alabama,  near  its  junction 
with  the  Tennessee  river,  and  is  common  in  the 
vicinity  of  Nashville,  Tennessee.  This  small  species 
is  related  to  U.  subtentus,  but  is  very  obviously  dis- 
tinct. It  is  proportionally  shorter  than  the  acutissimus, 
and  has  more  obvious  beaks,  but  young  individuals 
much  resemble  the  latter  species,  as  may  be  observed 
in  fig.  4.  In  some  specimens  the  posterior  undula- 
tions are  large  and  profound,  in  others  more  nume- 
rous and  not  so  distinct. 


UNIO  INTERRUPTUS. 

Plate  XLVIII. 

DESCRIPTION. 

Shell  subtriangular,  disks  flattened;  umbones  broad, 
flattened,  summits  obtusely  rounded;  posterior  slope 
much  depressed;  umbonial  slope  abruptly  rounded, 
nearly  terminal;  epidermis  brownish-yellow,  wrinkled, 
except  on  the  umbo;  rays  numerous,  narrow,  inter- 
rupted, of  a  dark  olive  colour;  on  the  umbonial  and 
posterior  slopes  consisting  of  series  of  small  quad- 
rangular spots;  within  white;  cardinal  and  lateral 
teeth  very  robust;  anterior  and  posterior  muscular 
impressions  deeply  impressed. 

SYNONYMES. 

U.  interrupta,  Raf.    Ann.  gen.  des  Sc.  Phys.,  vol.  v.  p.  36. 

Say.   Amer.  Conch.,  No.  6.     Ferr.   Mag.  de  Zool. 
U.  brevidens,  Lea.     Trans.  Amer.  Phil.   Soc,  new  series,  vol. 

iv.  p.  75,  pi.  vi.  fig.  6. 
Cab.  J.  N.  S.,  No.  1114. 


89 

OBSERVATIONS. 

Inhabits  Cumberland  river  near  Nashville,  Ten- 
nessee, and  Elk  river,  near  the  muscle  shoals,  Ala- 
bama. 

In  outline  it  somewhat  resembles  Unio  lineolatus, 
but  more  nearly  approaches  the  penitus.  The  rays, 
very  wide  umbo,  and  the  proportionally  shorter  out- 
line distinguish  it  from  the  latter  species.  The  lower 
figure  represents  the  female. 


UNIO  PLEXUS. 

Plate  XLIX.— Figs.  1,  2. 

DESCRIPTION. 

Shell  suboval,  ventricose;  posterior  margin  trun- 
cated or  obtusely  rounded;  posterior  slope  with  nar- 
row ribs;  umbo  flattened,  with  longitudinal  undula- 
tions; umbonial  slope  subangulated;  beaks  eroded, 
not  prominent;  epidermis  nearly  black,  wrinkled; 
within  purple;  cardinal  teeth  direct;  anterior  muscular 
impression  very  rough. 

Cab.  Ji.  N.  S.,  No.  20421. 

OBSERVATIONS. 

This  species  was  sent  from  Vera  Cruz  by  the 
American  consul,  Dr.  Marmaduke  Burrough.  I  am 
unacquainted  with  its  habitat.  The  larger  speci- 
men, of  which  an  outline  is  given  on  the  plate,  much 
resembles  U.  niger,  but  the  undulations  on  the  urn- 
bones,  the  proportional  length  in  the  smaller  speci- 

M 


90 


men,  and  other  characters,  render  it  sufficiently 
distinct.  It  has,  perhaps,  more  general  resemblance 
to  Unio  trapezoides  than  to  any  other  species. 


UNIO  HETERODON. 

Plate  XLIX.— Fig.  3. 

DESCRIPTION. 

Shell  rhomboidal-ovate,  ventricose,  valves  thin; 
ligament  margin  short,  elevated,  parallel  with  the 
basal  margin;  umbonial  slope  rounded;  beaks  decor- 
ticated; basal  margin  straight  in  the  middle;  posterior 
extremity  rounded  or  very  obtusely  angulated,  a  little 
above  the  line  of  the  base;  within  bluish;  cardinal 
tooth  in  the  left  valve  trilobed;  in  the  right  valve, 
single,  elongated,  oblique,  compressed;  lateral  teeth 
slightly  curved,  double  in  the  right  valve. 

SYNONYME. 

U.  heterodon,  Lea.     Trans.  Amer.  Phil.  Soc,  new  series,  vol. 

iii.  p.  428,  pi.  viii.  fig.  11. 
Cab.  A.  N.  S.t  No.  20425. 

OBSERVATIONS. 

Inhabits  the  Schuylkill  and  other  rivers  in  Penn- 
sylvania. This  interesting  little  species  was  first 
found  by  Messrs.  Mason  and  Hyde,  and  my  father 
suggested  the  name  of  heterodon,  which  Mr.  Lea  has 
adopted.  It  is  related  to  U.  viridis  and  compressus, 
but  the  double  cardinal  teeth  being  in  the  right  valve 
will  distinguish  it  from  every  other  species. 


91 


UNIO  LIENOSUS. 

VARIETY    CONSTRICTUS. 
Plate  XLIX.— Fig.  4. 

DESCRIPTION. 

Shell  elliptical,  ventricose;  beaks  rather  prominent, 
undulated,  distant  from  the  anterior  margin;  posterior 
side  furrowed,  contracted  at  base;  posterior  angle 
much  above  the  line  of  the  base;  epidermis  obscurely 
rayed;  within  white;  cardinal  teeth  robust. 

Cab.  A.  N.  S.,  No.  20423. 

OBSERVATIONS. 

Inhabits  North  river,  Rockbridge  county,  Virginia. 
Several  specimens  of  this  variety  exhibit  the  peculiar 
groove  on  the  posterior  side,  which  has  suggested  the 
name.  In  other  respects  it  agrees  with  U.  lineosus 
of  the  south-western  streams,  except  that  the  cardi- 
nal teeth  are  more  robust. 


UNIO  STRAM1NEUS. 

Plate  L. — Fig.  1. 
DESCRIPTION. 


Shell  ovate,  ventricose;  disk  with  coarse  prominent 
lines  of  growth;  umbo  with  numerous  undulated  plicae; 
umbonial  slope  undefined;  ligament  margin  elevated; 


92 

anterior  side  slightly  contracted  or  furrowed  from 
beak  to  base;  basal  margin  slightly  emarginate;  epi- 
dermis straw-coloured,  polished;  within  white;  car- 
dinal teeth  double  in  each  valve;  lateral  teeth  slightly 
arcuate. 

SYNONYME. 

U.  stramineus,  Nob.     New  Fresh  Water  Shells,  pi.  vii.  fig.  3. 
Cab.  A.  N.  S.,  No.  20420. 

OBSERVATIONS. 

Inhabits  brooks  or  mill  streams  in  Greene  county, 
Alabama. 

This  species  may  be  compared  to  some  varieties 
of  siliqaoideus,  but  is  sufficiently  distinct,  being  desti- 
tute of  rays  on  the  disk,  and  having  remarkably 
prominent  lines  of  growth.  The  siliqiioideus  has  not 
been  found  in  Alabama. 


UNIO  PATULUS. 

Plate  L. — Fig.  2. 

DESCRIPTION. 

Shell  ovate;  convex  anteriorly,  and  compressed 
and  cuneiform  posteriorly;  substance  of  the  shell  thick 
on  the  anterior  and  thin  on  the  posterior  side;  beaks 
not  terminal,  prominent,  undulated,  almost  contigu- 
ous; umbonial  slope  undefined  or  obtusely  rounded; 
epidermis  brownish-yellow,  with  broad  interrupted 
green  rays  composed  of  fasciculi  of  hair  like  lines; 
within  white;   cardinal  teeth,  in  the  left  valve  pro- 


93 


foundly  diverging;  in  the  right  valve  single,  robust, 
sulcated;  lateral  teeth  rectilinear. 


SYNONYME. 


U.  patulus,  Lea.    Trans.  Amer.  Phil.  Soc,  new  series,  vol.  iii. 

p.  441,  pi.  xii.  fig.  20. 
Cab.  Ji.  N.  S.,  No.  20424. 


OBSERVATIONS. 


Inhabits  the  rivers  of  Tennessee  and  Kentucky, 
and  appears  to  be  comparatively  rare.  It  may  be 
distinguished  from  U.  clava  by  its  less  oblique  and 
more  compressed  form;  and  the  beaks  are  less  pro- 
minent and  not  terminal.  The  beaks  are  acutely 
pointed  at  the  apex,  and  nearly  touch  each  other; 
and  they  are  somewhat  flattened  on  the  summit  and 
have  tubercular  undulations.  It  is  probable  that  U. 
oviformis  is  but  a  variety  of  this  species. 


UNIO  HEMBELI. 

Plate  LI. — Fig.  1. 
DESCRIPTION. 

Shell  elliptical,  convex,  posterior  extremity  angular, 
much  above  the  line  of  the  base;  posterior  slope  with 
obtuse  undulations;  beaks  eroded,  scarcely  elevated 
above  the  dorsal  line;  umbonial  slope  undefined;  epi- 
dermis dark  brown,  becoming  black  with  age,  much 
wrinkled;  within  white;  cardinal  teeth  robust,  double 
in  each  valve,  direct,  profoundly  striated. 

Cab.  A.  N.  S.,  No.  20422. 


94 

OBSERVATIONS. 

Many  specimens  of  this  shell  was  sent  from  New 
Orleans  in  company  with  the  declivis,  Mortoni,  pur- 
puratus,  &c,  but  the  locality  was  not  given.  It  has 
some  affinity  with  the  subtenttis,  but  is  thinner  in  sub- 
stance, and  differs  widely  in  the  posterior  angle. 
It  is  never  rayed,  whilst  that  species  has  well  marked 
interrupted  rays.  Some  specimens  which  are  desti- 
tute of  the  undulations  on  the  posterior  slope  might 
be  confounded  with  U.  complanatus. 

It  is  named  in  compliment  to  my  friend  William 
Hembel,  Esq.,  Vice-President  of  the  Academy  of 
Natural  Sciences  of  Philadelphia. 


END  OF  VOL.   I. 


INDEX 


page.  pl.    fig. 
Unio  fasciatus,             -            -            -            -            -311 

OVATUS,  -----                  4  2 
CLAVA,         -                  -                  -                  -                 -                  -531 

decisus,  -  -  -  -  -  632 

reflexus,  -  -  -  -  -741 

flexuosus,  -  -  -  -  -  842 

phillipsii,  -  -  -  -  -951 

metanevrus,                -            -            -                       10  5        2 

MORTONI,                       -                 -                 -                  -                 -11  61 

FRAGOSUS,  -                 -                  -                  -                  -12  62 

COSTATUS,                    -                  -                 -                  -                 -17  7 

RETUSUS,  -----               19  8 

PARVUS,     -              -              -              -              -              -20  91 

GLANS,  -                -                -                -                                21  9           2 

siliquoideus,        -            -            -            -           -22  101 

radiatus,  -            -            -            -            -24  102 

pectorosus,          -            -            -            -            -25  111 

fasciolus,  -            -            -            -            -26  112 

congaRjEus,           -            -            -            -            -    27  12         1 

masoni,  -             -             -             -             -           28  12         2 

coccineus,            -            -            -            -            -29  131 

catillus,  -            -            -            -            -30  132 

productus,           -            -            -            -            -    31  14        1 

lanceolatus,              -            -            -            -          32  14        2 

RECTUS,      -                  -                   -                 -                  -                 -      33  15 

crassus,  -             -             -             -             -34  16 

viridis,     -            -            -            -            -            -35  17         1 

ochraceus,  -            -            -            -            -          37  17        2 

NASUTUS,                       -                 -                  -                 -                 -      38  18             1 

ICTERINUS,  -                -                -                -                               39  18           2 

cariosus,               -            -            -            -            -40  19 

mytiloides,  -            -            -           -            -          41  20 

dilatatus,            -            -            -            -            -42  21 

tuberculatus,            -           -            -            -          43  22 

declivis,                -             -             -             -             -    45  23         1 

blandingianus,           -           -            -           -          46  23        3 

personatus,          -            -            -            -            -    47  24 

cordatus,  -            -            -           -                      48  25 


IV 

PAGE.  PL.      FIG. 

Unio  NIGER,          -  -                 -                 -                 -                 -      49  26 

GIBBOSUS,              -  -                 -                  -                                  50  27             1 

PEROBLIQUUS,  -                 -                  -                 -                  -      51  27            2 

TERES,                    -  -                  -                  -                  -               52  28 

SAGERI,        -  -                 -                 -                  -                  -53  29             1 

LAPILLUS,           -  -               -               -               -            54  29          2 

FRAGILIS,  -                  -                 -                  -                  -      55  30 

ALATUS,                 -  -                 -                  -                                 56  31 

INFLATUS,  -       -       -       -       -   57  32 

LEPTODON,     -  -       -       -       -      58  33 

ellipsiformis,  -            -            -            -            -    60  34        1 

lienosus,         -  -            -            -            -          60  34        2 

stapes,     -  -            -            -            -            -    62  35         1 

intermedius,  -            -            ...          63  35         1 

occidentals,  -           -           -           -           -    64  36        1 

collinus,         -  -            -            -                       65  36         2 

sowerbyanus,  -            -            -            -            -    66  37         1 

politus,           -  -            -            -            -          67  37        2 

nexus,      -  -            -            -            -            -    68  38         1 

GREEN1I,              -  -                -                -                              69  38           2 

SHEPARDIANUS,  -                 -                 -                 -                  -      70  39 

tOMPRESSUS,      -  -                 -                  -                 -               71  40             1 

capsjeformis,  -            -            -            -            -    72  40        2 

subplanus,      -  -            -            -            -          73  41         1 

flavus,     -  -            -            -            -            -    74  41         2 

capax,              -  -             -             -                        75  42 

rudis,       -  -            -            -            -            -    76  43         1 

obliquus,         -  -            -            -            -          77  43        2 

apiculatus,  -            -            -            -            -    78  44         1 

prasinus,         -  -            -            -            -          79  44        2 

nodulatus,  -            -            -            -            -    80  45        1 

feULLATUS,         -  -              -              -                           82  45          2 

STEGARIUS,  -                  -                  -                  -                  -      83  46            1 

DROMAS,             -  -              -              -              -            84  46          2 

subtentus,  -            -            -            -            -    85  47        1 

acutissimus,  -            -            -            -          86  47        2 

conradius,  -           -           -           -           -    87  47        3 

interruptus,  -            -            •            -          88  48 

plexus,     -  -            -            -            -            -    89  49         1 

heterodon,     -  -            -            -           -          90  49        3 

lienosus,  -            -            -            -            -91  49        4 

stramineus,    -  -            -            -            -          91  50         1 

patulus,  -             -             -             -             -     92  50         2 

HEMBELI,             -  -                  -                  -                                 93  51             1 


95 

UNIO  CERINUS. 

Plate  LII. 
DESCRIPTION. 

Shell  triangular,  subrhomboidal,  compressed;  disks 
flattened,  slightly  undulate;  ligament  margin  slightly 
declining;  posterior  margin  obliquely  truncated,  ex- 
tremity obtusely  angulated;  umbonial  slope  angulated; 
beaks  decorticated,  not  prominent;  anterior  margin 
truncated  above;  basal  margin  widely  and  slightly 
emarginate;  epidermis  brownish-yellow;  within  white 
with  wax-yellow  stains;  cardinal  teeth  direct,  robust, 
single  in  one  valve  and  double  in  the  other;  lateral 
teeth  rectilinear. 

OBSERVATIONS. 

A  few  specimens  of  this  species  were  sent  me  from 
New  Orleans  by  Mr.  Josiah  Hale.  It  probably  in- 
habits the  waters  of  Louisiana,  not  far  from  New 
Orleans.  The  two  most  characteristic  species  of 
Louisiana  were  contained  in  the  box  of  specimens,  U. 
Mortoni  and  U.  Hydianus,  Lea,  and  also  U.  Hcmbeli. 

It  has  a  general  resemblance  to  U.flavus  and  sub- 
planus;  from  the  former  of  which  it  may  be  distin- 
guished by  its  much  less  prominent  beaks,  more 
compressed  disks  and  proportionally  longer  outline: 
it  differs  from  the  latter  in  having  a  broader  umbo, 
emarginate  base,  longer  ligament  margin,  less  oblique 
posterior  margin,  truncated  anterior  margin,  and 
more  robust  cardinal  teeth.     Old  shells  have  some- 

N 


96 


what  the  outline  of  U.  niger,  as  represented  in  the 


lower  figure. 


UNIO  LATIRADIATUS. 
Plate  LIII. 

DESCRIPTION. 

Shell  elliptical,  rather  thin;  posterior  side  produced, 
extremity  obtuse,  and  subangulated;  umbonial  slope 
rounded,  undefined;  beaks  slightly  prominent,  with 
rather  coarse  angulated  plica?;  basal  margin  arcuate; 
posterior  margin  rectilinear  and  very  oblique;  epider- 
mis yellow,  polished,  with  very  broad  and  intermediate 
slender  green  interrupted  rays;  within  white,  highly 
iridescent;  cardinal  teeth  direct,  pyramidal;  posterior 
side  shewing  the  exterior  rays  through  the  substance 
of  the  shell. 

SYNONYME. 

U.  interruptus,  Lea.  Trans.  Amer.  Philos.  Soc,  new  series, 
vol.  vi.,  pi.  vi.,  p.  15,  fig.  15. 

OBSERVATIONS. 

Inhabits  streams  in  the  vicinity  of  Nashville,  Ten- 
nessee. I  have  received  a  fine  series  through  the 
kindness  of  Richard  O.  Currey  and  Samuel  M.  Edgar 
of  Nashville.  The  species  is  remarkable  for  the 
broad  interrupted  rays,  and  resembles  in  this  charac- 
ter and  in  general  aspect  U.  tceniatus;  it  is,  however, 
a  thinner  and  less  ventricose,  as  well  as  more  elon- 


97 

gated  shell,  and  will  hardly  be  confounded  with  it. 
The  name  interruptus  cannot  be  retained  for  this 
shell,  since,  if  Rafinesque's  species  be  rejected,  it 
must  be  applied  to  the  trapezoides  of  Lea,  in  right  of 
priority,  as  the  latter  was  described  by  Say  under 
the  name  of  interruptus.  The  largest  specimen 
measures  3i  inches  in  length. 


UNIO  SUBINFLATUS. 

Plate  LI V.— Fig.  1. 

DESCRIPTION. 

Shell  ovate-oblong,  posterior  side  slightly  ventri- 
cose;  ligament  margin  elevated,  slightly  ascending; 
umbones  very  wide;  beaks  distant  from  the  anterior 
margin,  not  in  the  least  prominent,  decorticated; 
anterior  margin  rounded,  not  very  obtuse;  umbonial 
slope  scarcely  angulated;  posterior  extremity  obtuse, 
direct;  epidermis  reddish-brown  and  olivaceous, 
smooth,  with  unequal  green  rays;  within  pale  purple; 
cardinal  teeth  robust,  not  very  prominent,  sulcated; 
lateral  teeth  arcuate,  rather  thick. 

SYNONYME. 

U.  complanatus,  variety  subinflatus,  Nob.     New  Fresh 

Water  Shells,  Appendix,  p.  5,  pi.  ix. ,  fig.  2. 
Cab.  Jl.  N.  S.,  No.  20426. 

OBSERVATIONS. 

I  found  this  species  several  years  since  in  the 
Savannah  river,  at  Augusta,  Georgia,  and  considered 


98 

it  a  variety  of  IJ.  complanatus,  but  a  re-examination 
of  the  specimens  has  led  me  to  regard  it  as  a  distinct 
species.  It  is  proportionally  longer,  and  may  always 
be  recognised  by  its  elevated  ligament  margin,  and 
the  remarkable  inflation  of  the  upper  part  of  the 
umbonial  slope.  The  sinus  of  the  cartilage  is  much 
shorter  than  in  the  variety  of  the  allied  species  which 
it  most  nearly  resembles,  (U.  cariniferus,  Lam.)  the 
posterior  margin  more  oblique,  and  the  umbo  is  much 
wider;  it  has  also  more  robust  and  much  less  promi- 
nent cardinal  teeth;  a  much  smoother  and  less 
wrinkled  epidermis,  and  the  interior  is  never  dark 
purple. 


UNIO  ANGUSTATUS. 

Plate  LIV.— Fig.  2. 
DESCRIPTION. 

Shell  elliptical,  elongated,  ventricose;  disks  slightly 
contracted  obliquely  from  beak  to  base;  ligament  and 
basal  margins  parallel;  anterior  dorsal  margin  ele- 
vated, obtusely  rounded  at  tip;  posterior  margin 
rectilinear,  profoundly  oblique;  extremity  obliquely 
truncated,  the  inferior  angle  or  tip  acute;  considera- 
bly above  the  line  of  the  base;  umbonial  slope  angu- 
lated,  rectilinear;  beaks  decorticated,  slightly  promi- 
nent, acute,  approximate;  basal  margin  slightly 
contracted  in  the  middle,  epidermis  brown  olivaceous, 
obscurely  rayed:  within  pale  chocolate  colour  and 


99 


highly  polished;  cardinal  teeth  very  prominent,  ob- 
lique; lateral  teeth  long  and  rectilinear. 


SYNONYME. 

U.  angustatus,  Lea.     Trans.  Amer.  Phil.  Soc,  new  series, 
vol.  iv.  p.  114,  pi.  xvii.  fig.   43. 

OBSERVATIONS. 

Inhabits  the  tide  waters  of  South  Carolina.  It  has, 
perhaps,  more  general  resemblance  to  U.  nasutus  and 
Fisherianus  than  to  any  other  species,  but  is  too  ob- 
viously distinct  to  need  a  careful  comparison  with 
either.  I  doubt  whether  it  occurs  in  any  stream 
north  of  the  Carolinas. 


UNIO  EXCULTUS. 

Plate  L  V.— Fig.  1. 

DESCRIPTION. 

Shell  subrhomboidal,  thin,  ventricose;  ligament 
margin  straight,  rounded  at  tip,  scarcely  oblique; 
beaks  rather  distant,  slightly  prominent,  decorticated, 
with  traces  of  oblique  plicae,  and  distant  from  the 
anterior  extremity;  anterior  margin  regularly  rounded; 
posterior  margin  rectilinear,  very  oblique;  extremity 
truncated  or  obtusely  rounded,  scarcely  angulated; 
epidermis  olive-brown,  with  dark  concentric  bands, 
polished;  within  bluish,  with  wax-yellow  stains,  and 
highly  iridescent;   cardinal  teeth  compressed,  elon- 


100 

gated,  very  oblique;  the  posterior  lobe  of  the  tooth  in 
the  left  valve  rudimentary  and  remote;  muscular  im- 
pressions large,  the  anterior  ones  slightly  impressed; 
accessory  cacatrix  remarkably  large. 

Cab.  «/?.  N.  S.,  No.  20427. 

OBSERVATIONS. 

The  exterior  aspect  of  this  shell  is  remarkably  like 
that  of  an  Anodonta,  and  the  resemblance  is  main- 
tained in  the  highly  polished  and  iridescent  interior; 
but  the  teeth  are  remarkably  well  defined  for  so  thin 
a  shell;  middle  aged  shells  have  very  nearly  the  out- 
line of  U.  Saycmns,  but  cannot  be  confounded  with 
that  species,  on  account  of  their  large  size,  polished 
and  iridescent  interior  and  very  different  cardinal 
teeth.  It  differs  from  U.  tetralasmus,  Say,  in  being 
portionally  shorter  and  wanting  the  important  cha- 
racter of  a  double  lateral  tooth  in  each  valve.  Like 
that  species,  the  sayanus  and  camptodon,  it  has  very 
oblique  plica;  on  the  beaks. 

Several  specimens  of  different  ages  were  sent  me 
from  New  Orleans  by  Mr.  Josiah  Hale. 


UNIO  PULLUS. 

Plate  L  V.— Fig.  2. 
DESCRIPTION. 


Shell  elliptical,  inflated,  particularly  about  the 
umbo  and  umbonial  slope;  disks  slightly  contracted 
towards  the  middle;  ligament  margin  elevated,  not  in 


101 

the  least  declining;  posterior  margin  very  oblique, 
rectilinear;  extremity  obtusely  rounded,  considerably 
above  the  line  of  the  base;  beaks  decorticated, 
slightly  prominent;  umbonial  slope  rounded;  epider- 
mis very  dark  olivaceous,  wrinkled;  within  chocolate 
purple;  cardinal  teeth  oblique,  single  in  one  valve  and 
double  in  the  other;  cavity  of  the  umbo  and  posterior 
side  very  capacious. 

OBSERVATIONS. 

A  small  species  found  by  Dr.  William  Blanding  in 
the  Wateree  river,  South  Carolina.  It  resembles  the 
U.  parvus,  but  differs  in  having  a  much  less  wrinkled 
epidermis,  and  inflated  umbonial  slope,  more  obtuse 
posterior  extremity,  but  more  obviously  in  the  dark 
purple  colour  of  the  interior.  Since  the  figure  was 
drawn,  I  have  seen  a  larger  specimen  in  the  cabinet 
of  Mr.  Vanuxem,  from  the  Warm  Springs  of  North 
Carolina.  It  is  less  inflated  and  more  regularly 
elliptical  than  the  Wateree  shell. 


UNIO  MELINUS. 

Plate  LVX— Fig.  1. 
DESCRIPTION. 

Shell  oval,  slightly  ventricosc,  moderately  thick, 
slightly  contracted  from  beak  to  base;  beaks  promi- 
nent, with  fine  crowded  undulations;  ligament  margin 
elevated,  not  oblique;  posterior  margin  oblique,  ex- 
tremity obtusely  rounded;  umbonial  slope  rounded; 


102 

epidermis  yellow,  polished,  with  numerous  obsolete 
rays;  within  white;  cardinal  teeth  double  in  each 
valve,  oblique,  prominent;  lateral  teeth  lamellar,  very 
prominent. 

OBSERVATIONS. 

I  found  a  few  specimens  of  this  species  about  two 
years  since  in  Salina  lake,  New  York,  and  delayed 
the  publication  of  it  in  the  expectation  of  obtaining 
other  specimens.  The  young  and  adult  shells,  how- 
ever, are  before  me,  and  present  a  marked  difference 
to  either  cariosus  or  siliquoideus,  the  two  kindred 
species  which  abound  in  the  neighbouring  waters. 
It  is  proportionally  shorter  and  less  inflated  than  the 
latter,  and  differs  more  obviously  in  being  destitute 
of  distinct  rays.  It  is  proportionally  longer,  less 
inflated,  and  has  a  longer  ligament  margin  than  the 
cariosus;  the  cardinal  teeth  are  very  different. 


UNIO  SAYANUS. 
Plate  LV£— Fig.  2. 

DESCRIPTION. 

Shell  subrhomboidal,  rather  thin,  slightly  ventri- 
cose;  beaks  prominent,  obliquely  plicated;  anterior 
margin  obtusely  rounded;  ligament  margin  scarcely 
declining,  straight,  angulated  at  tip;  umbonial  slope 
rounded;  posterior  margin  subrectilinear,  oblique,  ex- 
tremity rather  acutely  angulated,  the  angle  being 
considerably  above  the  line  of  the  base;  basal  margin 


103 

very  slightly  contracted  anterior  to  the  middle;  car- 
dinal teeth  compressed  and  oblique;  within  bluish- 
white. 

SYNONYMES. 

U.  sayi,  Ward,  Silliman's  Journal,  vol.  xxxv. ,  pi.  3.  fig.  1. 
U.  declivis,  nob.,  p.  45,  pi.  xxiii.  fig.  1  of  this  work. 

OBSERVATIONS. 

This  shell  I  found  several  years  since  in  a  small 
stream  in  Greene  county,  Alabama,  and  supposed  it 
to  be  a  perfect  specimen  of  the  declivis  of  Say,  but 
it  differs  from  that  species  in  having  a  narrower 
umbo,  plicated  obliquely  on  the  summit,  a  lighter 
coloured  and  smoother  epidermis,  and  especially  in 
wanting  the  "rostrum  or  prominent  angle"  of  Say's 
description  of  U^  declivis.  It  inhabits  the  canal  near 
Savannah,  where  it  was  found  by  Mrs.  Say;  also  the 
canal  at  Louisville,  Kentucky.  The  name  was  in- 
advertently given  as  Sayanus  instead  of  Sayi. 


UNIO  PLANILATERIS. 

Plate  L VII.— Fig.  1. 

DESCRIPTION. 

Shell  oblong-subovate,  rather  thin;  disks  flattened, 
compressed  anteriorly;  ligament  margin  elevated, 
parallel  with  the  base,  rounded  at  tip;  umbonial  slope 
inflated  and  angulated;  posterior  slope  flattened,  and 
having  on  its  upper  part  short,  slightly  prominent 


104 

oblique  lines;  beaks  not  prominent,  eroded;  basal 
margin  nearly  straight;  posterior  extremity  truncat- 
ed, direct;  epidermis  olivaceous,  with  crowded  pro- 
minent wrinkles,  and  with  rather  indistinct  green 
rays;  within  bluish  or  purplish;  cardinal  teeth  com- 
pressed, oblique. 

OBSERVATIONS. 

Some  specimens  of  this  shell  might  be  readily  mis- 
taken, without  close  examination,  for  U.  complanatus, 
but  the  species  is  more  nearly  allied  to  U.  congarceus. 
It  differs  in  having  a  more  elevated  ligament  margin, 
an  inflated  umbonial  slope,  and  is  proportionably 
longer.  It  is  a  very  abundant  species  in  the  Black 
Water  river,  Virginia,  and  occurs  also  in  the  Neuse 
river,  North  Carolina,  where  it  always  has  a  very 
rough  wrinkled  epidermis,  of  a  dark  colour.  The 
figure  is  from  a  specimen  found  by  Dr.  Blanding  in 
the  Yadkin  river,  North  Carolina,  where  it  is  more 
narrowed  posteriorly,  smoother,  thicker,  and  has  a 
lighter  coloured  epidermis  than  those  from  the  Black 
Water  and  Neuse  rivers.  One  specimen  is  quite 
thick  and  salmon  coloured  within. 


UNIO  METASTRIATUS. 

Plate  LVIL— Fig.  2. 
DESCRIPTION. 

Shell  subtriangular,  moderately  thick;  umbo  and 
disk  flattened,  but  forming  a  strongly  arcuate  line 


105 

from  beak  to  base;  beaks  rather  distant  from  the 
anterior  extremity,  eroded;  umbo  very  broad;  umbo- 
nial  slope  abruptly  rounded,  nearly  terminal;  posterior 
slope  with  slightly  prominent  radiating  lines;  poste- 
rior margin  nearly  direct;  margin  of  the  tip  obtuse; 
epidermis  wrinkled,  yellowish  brown,  with  capillary 
rays  over  the  umbo;  within  white;  cardinal  teeth 
direct,  robust;  lateral  teeth  short,  rather  thick,  very 
distant  from  the  cardinal  teeth. 

OBSERVATIONS. 

This  small  species  has  considerable  resemblance 
to  U.  interruptus,  but  the  disks  are  less  flattened,  the 
posterior  slope  much  less  depressed  and  wider,  the 
base  more  arcuated,  and  it  is  destitute  of  distinct 
dotted  rays.  I  found  a  few  specimens  in  the  Black 
Warrior  river,  near  Blount's  Springs,  Alabama. 


UNIO  CUNEUS. 

Plate  LVIII.— Fig.  1. 

DESCRIPTION. 

Shell  obliquely  cuneiform,  very  thick;  diameter 
through  the  umbones  profound;  disks  flattened  be- 
hind the  middle,  and  descending  wedge-shaped  to 
the  posterior  extremity,  which  is  obtuse;  beaks  much 
eroded,  terminal;  umbo  broad  and  very  prominent; 
umbonial  slope  rounded;  epidermis  dark  reddish- 
brown,  rough  and  much  wrinkled;  within  pink;  car- 


106 


dinal  and  lateral  teeth  very  thick;  posterior  cicatrix 
impressed. 


OBSERVATIONS. 


I  have  seen  but  one  specimen  of  this  Unio,  which 
was  found  by  Mr.  Featherstonhaugh  in  Little  Red 
river,  Arkansas,  during  his  investigations  of  the 
geology  of  that  region.  It  has  something  of  the 
interior  colour  and  general  outline  of  U.  catillus,  but 
the  diameter  through  the  umbones  is  far  greater. 
The  beaks,  if  they  ever  occur  perfect,  must  be  ex- 
ceedingly prominent. 


UNIO  LENIS. 

Plate  LVIII.— Fig.  2. 

DESCRIPTION. 

Shell  obovate,  rather  thin,  regularly  convex;  an- 
terior side  narrowed;  extremity  obtusely  rounded; 
posterior  side  dilated;  ligament  margin  elevated, 
forming  with  the  posterior  margin  an  arcuate  line; 
extremity  obtusely  rounded;  base  arcuate,  profoundly 
so  towards  the  posterior  extremity;  umbonial  slope 
rounded;  beaks  slightly  prominent,  with  rather  small 
plicae,  not  interrupted  by  well  defined  angles;  epider- 
mis brown-olive,  wrinkled,  with  rather  distant  slender 
green  rays;  within  white;  cardinal  teeth  crested, 
oblique,  single  in  one  valve,  and  double  in  the  other; 
lateral  teeth  distant  from  the  cardinal  teeth. 


107 


OBSERVATIONS. 


This  shell  may  readily  be  distinguished  from  U. 
cariosus  by  its  darker,  less  polished,  more  wrinkled 
epidermis,  more  regular  convexity  of  the  disks,  and 
by  the  rays  extending  over  the  whole  surface,  which 
is  very  rarely  the  case  with  the  former;  the  plicated 
beaks  constitute  another  point  of  difference.  Two 
specimens  were  sent  me  from  Illinois  by  Dr.  Fussel, 
who  found  them  in  the  upper  part  of  White  river. 


UNIO  HEROS. 

Plate  LIX. 

DESCRIPTION. 

Shell  oval,  somewhat  oblong,  with  large  distinct 
undulations,  three  or  four  in  number,  directed  to- 
wards the  posterior  margin,  and  not  proceeding  di- 
rectly from  the  umbo;  surface  with  a  few  abbreviated 
transverse  lines,  placed  without  any  regularity;  umbo 
placed  far  forward,  not  prominent,  hardly  elevated 
above  the  general  curvature,  more  or  less  literate 
with  short  irregular  lines  or  slight  elevations;  hinge 
margin  compressed,  nearly  rectilinear,  prominently 
angulated  or  subalated  at  tip;  in  the  more  perfect 
specimens  with  numerous  connected  regular  lines, 
curved  to  the  edge  and  undulating  it;  posterior  mar- 
gin rectilinear  from  the  extremity  of  the  hinge  margin 
to  the  rounded  inferior  half,  and  undulated  by  the  tip 
of  the  grooves  of  the  disk;  anterior  margin  very 
short,  regularly  rounded;  base  very  obtusely  rounded, 


108 

in  many  specimens  a  little  contracted  hear  the  pos- 
terior termination;  within  bluish-white,  pelaceous. 

SYNONYMES. 

U.  heros,  Say,  Disseminator  of  Useful  Knowledge,  vol.  ii.,  p. 

291,  Sept.  1829.     American  Conch,  No.  vii.  pi.  xvi. 
U.  xjndulatus,  Say,  (not  Barnes,)  American  Conch,  pi.  16. 
U.  multiplicatus,  Lea,  Trans.  Amer.  Philos.  Soc,  (new  series) 

vol.  iv.  p.  70,  pi.  iv.,  1831. 
Cab.  A.  JV.  8.,  No. 

OBSERVATIONS. 

Say  remarks  of  this  species,  that  "it  resembles  the 
plicatns,  nob.,  but  on  comparison  it  will  be  observed 
to  differ  essentially  from  that  common  species."  It 
is,  however,  more  nearly  related  to  the  costatus  of 
Rafinesque,  with  which  Say  at  one  time  confounded 
it,  although  he  had  previously  published  it  under  the 
name  of  heros.  In  his  synonomy  of  the  western 
species  of  Unio  and  Alasmodonta,  he  very  properly 
reclaims  the  species.  It  may  readily  be  distinguished 
from  the  costatus  by  the  small  letter-shaped  undula- 
tions on  the  umbo,  darker  epidermis,  and  by  other 
less  obvious  characters.  Say  informs  us  that  it  in- 
habits the  Wabash  river  and  tributaries.  I  am  in- 
debted to  Mrs.  Say  for  the  use  of  the  beautiful  and 
very  accurate  plate,  originally  published  in  the 
American  Conchology. 

Deshayes  considers  this  species  identical  with  the 
undulatus  of  Barnes,  and  refers  it  to  IT.  peruviana, 
Lam.* 

*  Anim.  sans  Vert.,  vol.  vi.  p.  533. 


109 
UNIO  SAXEUS, 

Plate  LX. — Fig.  1. 

DESCRIPTION. 

Shell  obovate,  ventricose,  rather  thin;  beaks  de- 
corticated, slightly  prominent,  summits  obtuse;  um- 
bonial  slope  subangulated  or  obtusely  rounded; 
ligament  margin  elevated,  not  oblique;  posterior 
margin  obliquely  rectilinear  or  slightly  concave; 
extremity  truncated,  direct;  basal  margin  regularly 
arcuated;  epidermis  yellowish-brown,  rather  ob- 
scurely rayed;  within  bluish;  cardinal  teeth  direct, 
compressed;  lateral  teeth  straight. 

OBSERVATIONS. 

I  found  a  few  individuals  of  this  species  in  the 
summer  of  1833  on  the  shore  of  the  Alabama  river 
at  Claiborne,  where  there  is  an  indurated  calcareous 
platform.  They  were  all  dead  shells;  and  like  its 
associate,  U.  arctatus,  this  species  I  never  saw  on  the 
muddy  shores  or  gravelly  bars. 


UNIO  COLLINUS. 

Plate  LX.— Fig.  3. 

OBSERVATIONS. 


Since  the  publication  of  this  species  in  a  former 
number  of  this  work,  I  have  received  a  few  specimens 


110 

from  the  same  locality  with  the  first  described,  which 
present  the  very  remarkable  character  of  spines,  one 
on  each  valve,  proceeding  in  an  erect  position  from 
near  the  middle  of  the  disk.  In  one  old  specimen 
there  is  no  trace  of  these  spines,  but  in  the  only  two 
middle  aged  specimens  I  received  the  spines  are  as 
well  developed  as  represented  in  the  figure.  A  spi- 
nous Unio,  no  doubt  the  same  species,  is  said  to 
occur  abundantly  near  Columbia  in  South  Carolina. 
This  is  a  smaller  species,  less  pointed  posteriorly, 
and  otherwise  distinct  from  the  U.  spinosus  of  Lea. 


UNIO  TRABALIS. 

Plate  LX. — Fig.  2. 
DESCRIPTION. 

Shell  oblong-ovate,  ventricose,  thick  anteriorly; 
anterior  side  short,  margin  obtusely  rounded;  poste- 
rior side  cuneiform,  produced,  obtusely  rounded  at 
the  extremity,  which  is  narrow;  hinge  margin  decli- 
ning; posterior  margin  slightly  contracted  just  above 
the  extremity  of  the  valve;  umbonial  slope  rounded; 
posterior  slope  flattened  or  concave,  in  old  shells 
furrowed;  beaks  eroded  and  rather  prominent;  basal 
margin  arched;  epidermis  smooth  and  polished,  dark 
olive-brown  tinted  with  green,  and  with  dark  green 
unequal  rays,  not  very  distinct;  within  dull  white  or 
slightly  salmon-coloured  anteriorly;  bluish  and  very 
iridescent  posteriorly;  cardinal  tooth  in  the  right 
valve  very  thick  and  direct,  in  the  left  valve  the  car- 


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UNIVERSITY  OF  ILLINOIS-URBANA 

594.1C76M  C001 

MONOGRAPHY  OF  THE  FAMILY  UNIONIDAE,  OR 


3  0112  017607323 


MSI               ''HEBlll 

■  ■  ;;  ■      ' 


